stats final exam

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Suppose we have a loaded die that gives the outcomes 1-6 according to the following probability distribution . die. 1. 2. 3. 4. 5. 6 prob0.1 0.2 0.3 0.2. 0.1

1/10

In my friends coin purse, Found 12 pennies. The ages , in years, of the pennies obtained by subtracting the year stamped on the coin from 2016 follow. 22, 14, 8, 1, 9, 0, 31, 2, 13, 3, 11, 10 Rounding to the nearest tenth, the mean and the median of this distribution (in years) are :

10.3 and 9.5

What is the interquartile range (IQR) for these data?

2.65 hours

At a certain diver's license testing station, only 40% of all new drivers pass the behind-the-wheel test the first time they take it. A sample of 50 new drivers from a certain high school found that 36% of them had passed the test the first time. Which of these numbers is a parameter

40%

A violin student records the number of hours she spends practicing during each of the nine consecutive weeks: 6.2, 5, 4.3, 7.4, 5.8, 7.2, 8.4, 1.2, 6.3 What is the median number of hours spent practicing per week during this period?

6.20 hours

a refrigerator contains 6 apples, 5 oranges, 10 bananas, 3 pears, 7 peaches, 11 plums, and 2 mangoes. Imagine you stick your hand into the fridge and pull out a piece of fruit at random. What is the sample space for your action?

S= (apple, orange, banana, pear, peach, plum, mango)

Scatterplots are used to illustrate

Two quantitative variables.

You recieve faxes with six bids (in millions of dollars): 2.2, 1.3, 1.9, 1.2, 2.4, and x, where x is some number that is too blurry to read. Without knowing what x is, you know that the median:

must be at least 1.3 and no more than 2.2

a p value is always computed assuming that

the null hypothesis is true

a random variable x can take on the value 0, 1, 2, or 3. Which of the following is a possible possibility model for x?

x 0 1 2 3 p(x) 0.5, 0.3, 0.1, 0.1

Suppose classmates who graduated in 2004 compared their median incomes ten years later. The bar graph displays the median income, in thousands of dollars, for each classmate during the time intervals from 2005-2009 and 2010-2014. For individual with the largest dollar value increase in median income over the two time intervals, determine the amount of increase By what percentage did Roger's median income decrease over the two time intervals? Give in nearest percent

$11000 8%

A researcher at a large company has collected data on both the beginning salary and the current salary of 48 randomly selected employees. The least-squares regression equation for predicting their current salary from their beginning salary is y= -2532.7+2.12x. Kathy Jones started working for the company earning $19,000. She currently earns $40,000. What is the residual for Ms. Jones

$2,252.70

The given figure is a scatterplot of the price of a hot dog against the price of beer (per ounce) at 24 major league baseball parks in 2015. The line is the least-squares regression line for predicting the price of a hot dog from the price of beer. If another ballpark charges 0.60 dollar per ounce for beer, you predict the price of a hot dog to be close to

$5.50

a random variable x has a normal distribution with an unknown mean and a standard devation of 12. Suppose that we take a random sample size of n=36 and find a sample mean of x= 98. what is the 95% confidence interval for the mean of x?

(94.08, 101.92)

For each of the hypothetical data sets, determine whether a bar graph or a pie chart would be an appropriate way to display the data. In some cases, both types of graphs may be appropriate: -the percent of individuals with each of the following natural hair color s" black, brown, blond, red and other -the land area of each of the approximately 50 countries in europe -the number of college students who play basketball, baseball or soccer The proportion of traditional public schools in the region compared to the proportion of charter and private K-12 schools in that region.

- bar graph, pie chart -bar graph -bar graph - bar graph, pie chart

Suppose the pie chart shows the percentage of seats available for a a concert. Mezzanine left 25.5% Balcony 30% Orchestra left 15.5% Mezzanine right 20.0% Orchestra right 10% Please select the reasons why the pie chart is misleading.

-at least one section does not accurately represent its relative area - the sections of the pie chart do not add up to 100%

The summer monsoon rains bring 80% of India's rainfall and are essential for the country's agriculture. Records going back more than a century show that the amount of monsoon rainfall varies from year to year according to a distribution that is approximately normal with mean 852 milimeters and standard eviation 82mm. Use the 68, 95, 99.7 rule to answer the questions. Between what values do the monsoon rains fall in the middle 95% of all years? How small are the monsoon rains in the driest 2.5% of all years?

-between 688 and 1016mm -less than 688mm

Classify each described variable as quantitative

-hourly wage of employees -ages of academy award-winning actors in years -temperature in degrees celcius

Select the statements that describe a normal distribution.

-the normal distribution is a continuous distribution -the density curve is symmetric and bell-shaped -approximately 5% of values fall more than two standard deviations from the mean

Classify each described variable as categorical

-type of soda -survey answers containing options of disagree, neutral, or agree -a person's country or origin

A data set of the sample consists of five observations, {2, 2, 2, 2, 2}. What is the standard deviation?

The distribution of actual weights of 8oz wedges of chedder cheese produced at a dairy is normal with mean 8.1 oz ans standard deviation 0.2 oz. A sample of 10 of these cheese wedges is selected. What is the standard deviation of the sampling distribution of the mean?

0.0633 oz

The british government conducts regular surveys of household spending. The average weekly household spending on tobacco products and alcoholic beverages for each of 11 regions in Great Britain are recorded. A scatter plot of spending on tobacco versus spending on alcohol is given What is the most plausible value for the correlation between spending on tobacco and spending on alcohol?

0.08

Every year, the veterinary hospital at a major research university treats a number of horses that have stones called enteroliths in their guts. A sample of 20 years shows that on average about 2% of horses presenting at the veterinary hospital are treated for enteroliths. Some breeds of horses seem more prone to developing enteroliths than others. Below is a table with the distribution of enteroliths among the breeds. BreedArabianThoroughbredAppaloosaMorganQuarter horseProbability0.300.10?0.050.45 The probability that a horse arriving at the veterinary hospital is an Appaloosa horse is:

0.10

Birth weights at a local hospital have a Normal distribution with a mean of 110 oz and a standard deviation of 15 oz. The proportion of infants with birth weights between 125 oz and 140 oz is:

0.136

A survey of 303 drivers asked which size car they would consider purchasing. The given table shows the count of their responses by gender. 58. 63. 17. 138 79. 61. 25. 165 137. 124. 42. 303 The proportion of males who perfer a large car is

0.152

a carpet manufacturer is inspecting for flaws in the finished product. If there are too many blemishes, the carpet will have to be destroyed. If we assume the standard deviation of the numbr per flaws per square yard is 0.6, the sample mean, x, for the 10 square yards will have what standard evation?

0.19

The 94 students in a statistics class are catagorized by gender and by year in school. The numbers obtained are displayed in the table. 1. 2. 6. 17. 2. 31 23. 17. 13. 7. 3. 63 24. 19. 22. 24. 5 94 What proportion of the statistcs students in this class are sophomores.

0.202

0.25

the number of years of education of self employed individuals in the United states has a population mean of 13.6 years and a population standard deviation of 3 years.

0.3 years

the number of years of education of self-employed individuals in the united states has a population mean of 13.6 years and a population standard deviation of 3 years. If we survey a random sample of 100 self-employed people to determine the average number of years of education for the sample, what is the standard deviation of the sampling distribution of x, the sample mean?

0.3 years

Suppose that each of the numbers 0,1,2,3,4,5,6,7,8,9 is written on a piece of paper in a jar. If each number is equally likely, and x is the value of the number on the piece of paper, what is P(x > 5)?

0.4

Which of the following is a plausible correlation for a person's height and age from birth to age 10?

0.89

You are using the table of random digits to choose a simple random sample of 6 students from a class of 30 students. You label the students 01 to 30 in alphabetical order, and then select a simple random sample Which is a possible sample that could be obtained

04, 18, 07, 13, 02, 05

an urn contains 2 red and 2 green marbles. The probability distribution for the number of red marbles is given below red. 0. 1. 2. 3 prob 1/8. 3/8 3/8 1/8 The probability of 2 or more red marbles if given by

1.2

suppose that x is a normally distributed random variable with an unknown mean u and known standard devation 6. If we take repreated samples of size 100 and compute the sample means x, 95%

1.2

In an experiment for a new drug to determine the most effective dose and medication. 5-, 10-. 15-, or 20 mg dose

the following histogram represents the distribution of acceptance rates (percent accepted) among 25 business schools in 2004. In each class interval, the left endpoint but not the right is included, so the class intervals are 10 greater than/equal to rate < 15, 15 greater than/ equal to rate < 20, etc The number f schools with an acceptance rate over 30% is

13.6 years

Suppose students who enter kindergarten at Sotomayor Elementary school take a standardized vocabulary assessment. The scores on the assessment produce a normal density curve shown. mean= median= standard deviation=

150 150 11

I want to take a survey of students currently enrolled in my statistics course. There are 250 of them, so i number them from 001 to 250 in alphabetical order 69041 65817 87174 09514 8174 06423 93758 23612 17894 If i use the portion of the given random number table to select the first five students to be interviewed, which 5 numbers will be seleted?

174, 095, 148, 064, 239

Consumers' Union measured the gas mileage per gallon of 38 automobiles on a special test track. The bar graph given shows the information about the country of manufacture of the 38 cars that Consumers' Union used. Approximately what percent of cars used were from Japan?

18%

I want to take a survey of the students currently enrolled in my statistics course. There are 200 students in my class, so I number them from 001 to 200 in alphabetical order. Use the portion of the random number table below to select the numbers for the first five to be interviewed. 69041 61817 87174 09514 8174 06423 93758 23612 16894

181, 174, 095, 148, 064

For this density curve, the median is

The scores of adults on an IQ test are approximately Normal with mean 100 and standard deviation 14. Clara scores 129 on such a test. What is her z-score? rounded to three decimals

2.071

Scores on a university exam are Normally distributed with a mean of 88 and a standard deviation of 4. The professor teaching the class declares that a score of 80 or higher is required for a grade of at least "B." Using the 68-95-99.7 rule, what percent of students failed to earn a grade of at least "B"?

2.5%

Scores on a university exam are normally distributed, with e mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least a C. Using the 68-95-99.7 rule, what percent of students score below a 62?

2.5%

a high level of glucose in the blood is an indication of diabetes, which is becoming more prevalent in the US. Diabetes can lead to many complications, such as blindness and heart disease. A random sample of 180 individuals had their glucose level measured. The results are displayed in the graph; Which value might be considered an outlier?

215

A sample was taken of the salaries of four employees from a large company. The following are their salaries, in thousands of dollars, for this year. 33 31 24 36 The variance of their salaries is

an urn contains 2 red and 2 green marbles. The probability distribution for the number of red marbles is given below red. 0. 1. 2. 3 prob 1/8. 3/8 3/8 1/8 the probability of exactly 1 red marble is given by

3/8

30.27%, 47.07%, 22.67%

A large group of people was surveyed about their favorite movie genre. The participants had to give their age and choose their favorite genre from Action, Comedy, and Horror. ActionComedyHorrorTotal18-25 years old 238 450 312 1000 25-49 years old350 472 1781 000 50+ years old320 490 190 1000Total 908 1412 680 3000 What is the conditional distribution of age groups among the people who chose comedy?

31.87%, 33.43%, 34.70%

A recent survey of book critics asked 24 critics how many stars out of a possible 5 they gave to a recent novel from a popular author. The 24 critics' responses are summarized by the histogram below. Answer the following. Approximately, what percent of the 24 critics gave the book 2 stars or less?

33%

students at university x must be in one of the following class ranks: freshman, sophomore, junior or seniors. At university x, 35% of the students are freshamn and 30% are sophomores. IF a student is selected at random, the probability that he or she is either a junior or senior is

35%

36%

to assess the accuracy of a laboratory scale, a standard weight known to weigh 1 gram is repeatedly weighed a total of n times and the mean x of the weighings is computed

38,416

38/44

A recent survey of book critics asked 24 critics how many stars out of a possible 5 they gave to a recent novel from a popular author. The 24 critics' responses are summarized by the histogram below. Answer the following. What number of stars is the median in this data set i.e. what is the median rating?

Suppose that college studentst are asked to identifiy their preferences in political affiliation; democrat, republican or independent and in ice cream; strawberry, chocolate or vanilla. Suppose that their respoonses are represented in the two way table with some of the totals left for you to calculate dem 26. 43. 13. 82 rep 45. 12. 8. 65 indep 9. 13. 4 68. 25. 173 What percent of the respondents preferred chocolate?

46.2%

The given figure is a scatterplot of the price of a hot dog against the price of beer (per ounce) at 24 major-league ballparks in 2015. The line is the least-squares regression line for predicting the price of a hot dog from the price of beer. The slope of the line in the figure is closest to

5.0

56.3%

The 137 horses in a study on enteroliths, a type of stone in a gut, were housed either in a small paddock, a large paddock, a stall, or a grass pasture. Based on the bar chart, the percent of horses living in paddocks, large or small, is approximately

58%

Use the following information to answer questions (13-14). A Piano student records the number of hours he spends practicing during each of nine consecutive weeks. 6.2 5.0 4.3 7.4 5.8 7.2 8.4 1.2 6.3 What is the median number of hours spent practicing per week during this period?

6.2 hours

Suppose you received a score of 91 out of 100 on exam 1. The mean was 79 and the standard deviation was 8. What score do you need on exam 2 to do equally well, if the mean is 60 and the standard deviation is 12?

In a statistics course, a linear regression equation was computed to predict the final exam score from the score on the midterm exam. The equation of the least-square regression line was y=10+0.9x, where y represents the final exam score and x is the midterm exam score. Suppose Joe scores an 80 on the midterm exam. What would be the predicted value of his score on the final exam?

suppose that we compute a 90% z confidence interval for an unknown population mean u. Which of the following is a correct interpretation?

90% of all possible z confidence intervals computed from samples of the same size would contain u

Facebook remains the top choice of social media over all ages, with 65% using Facebook most often among those using social media sites. However, more visually oriented social networks such as snapchat and instagram continue to draw in younger audiences. When asked "which one social networking site or service do you use most often?" the results in the table show the top sites chosen by americans aged 12-24 who currently use any social networking site or service. Facebook 43% Instagram 18% Snapchat 15% Twitter 8% Google 4% Pinterest 3% What is the sum of percentages? What percent of Americans aged 12-24 use other social media sites most often? other social media sites? Would it be correct to display these data in a pie chart?

91 9 Yes. If you include an "other" catagory, a pie chart would be appropriate, as each person is only represented in one category and categories make up the whole.

An instructor in a large lecture class found, at the end of the semester, that the total point distribution in his class was approximately normal, with a mean of 530 and a standard deviation of 80. About what percent of students will score between 370 and 690?

95%

The given graph represents a population with a normal distribution Approximately what percent of the population represented by the shaded area?

97.5%

What is the difference between a histogram and a bar chart?

A bar chart displays a categorical variable on the horizontal axis, whereas a histogram does not.

The figures display three density curves, each with three points marked on them. Identify the points on density curve a where the mean and the median fall. Enter the letter of the term that corresponds to each choice. For example, if you are choosing "point A", enter the letter "A' in the answer blank. mean= median= B: mean and median C: mean and median

A: mean=C, median =B B: mean= B, median= B C: mean=A, median=B

A professor drew a side-by-side boxplots of the exam scores after giving a statistics exam to her classes (group 1 and group 2). Use these boxplots to answer the following. Which of the following is reasonable to say for Group 1?

About 50% of exam scores are between 70 and 90.

A Normal distribution:

All of the answer options are correct -is symmetric -can be completely specified by a mean, u and a standard deviation, o -has an areas of exactly 1 underneath the density curve

A survey of radiostations was conducted following the attacks on the World Trade Center in 2001. One of the variables recorded was the region in which the station was located. In addition to the variable "region", the following information was collected: the quartile of the media market (top, second, third and fourth), state, rank, and share. The side-by-side boxplots of station rank, above, show

All of the answer options are correct -similar minimum ranks between regions -more variability in ranks of coast stations -different median ranks between the regions

A poll was conducted of more than 50,000 buyers of new cars, 90 days after the cars were purchased. The data on problems per 100 vehicles for cars made by Toyota and General Motors (GM) is given in the time plot below for the years 1998-2004. The solid line is for GM and the dashed line is for Toyota. Answer the following question assuming the number of problems per 100 vehicles as a measure of the quality of cars. Which of the following is a true statement?

All of the answer options are correct. -The difference in the number of problems per 100 vehicles between GM and Toyota is less than 30 year 2002 onward. -The number of problems was higher for GM than for Toyota in each year. -The quality of cars is getting better for both companies.

A large urban university wanted to estimate the average amount of money spent by all students on textbooks in the 2020 spring semester. To save postage, they decided to hand-delivered survey forms to 400 randomly selected students chosen just from those living on campus. 345 of these students completed and returned the survey. The Population in the university study is

All students enrolled at the university in the 2020 spring semester

A fair die is rolled and the sample space is given S = {1, 2, 3, 4, 5, 6}. Which statement is TRUE?

All the above choices are correct

Calculate the conditional distribution of movie genre by age group.

A 2017 study surveyed 10,478 children from Bangledesh about their handwashing habits. The data provided included descri[tive information about each child including age and birth-assigned sex, as well as each child's response to a question about handwashing. Identify each item or variable from the data set as a case, catagorical variable, quantitative variable or value

Case: subject number 3 Categorical variable: -residence, an indication of each subjects living circumstances -wash, a representation of each subject's response to whether they washed their hands after using the bathroom -sex, each subjects birth assigned sex Quantitative variable: age, each subject's age Value: the age of subject number 25

A firm wants to understand the attitues of its minority managers towards its sytem for assesssing managment performance. Adelaja Ahmadiani Barnees Bonds Burke Deis

Deis, Fernandez, Gemayel

The mean area u of the several thousand apartments in a new development by a certain builder is advertised to be 1100 square feet. The appropriate null and alternative hypotheses, Ho and Ha, for u are:

H0: u = 1100 and Ha: u<1100

is the mean age at whcih american children read first now under four years? if the population of all american children has a mean age of u years until they begin to read.

H0: u=4 and Ha: u <4

Which of the following is not "the basic principles of statistical design of experiments"? I. Placebo control II.Random assignment to treatments III. Using enough subjects IV. Control effects of lurking variables by using comparison

Which of the following statements about the correlation coefficient and the least-squares regression line is TRUE?

If we switch the explanatory and the response variable, then the correlation coefficient would not be changed.

Which of these choices is true for the slope of the least-squares regression line?

It has the same sign as the correlation

An administrator in charge of residential life services recently conducted a survey of undergraduate college students at a small university. A random sample of 300 students was selected from each class level (freshman, sophomore, junior, or senior). Each student was asked to complete and return a short questionnaire on the quality of campus residences. Some students returned the questionnaire; some did not. This is summarized in the table below. Class Returned No response Total Freshman 110 190 300 Sophomore 130 170 300 Junior 170 130 300 Senior 160 140 300 Which of the following conclusions seems to be supported by the data?

Juniors and seniors appear to be more likely to return the survey than freshmen and sophomores.

The Wechsler Adult Intelligence Scale (WAIS) is a common "IQ test" for adults. The distribution of WAIS scores for persons over 18 years of age is approximately Normal with a mean of 100 and a standard deviation of 15. What is the mean and standard deviation of the sampling distribution of the average WAIS score for an SRS of 10 people?

Mean = 100, Standard deviation = 4.7434

Missy took the ACT and was told her standard score (z score) is -1. Frank took the SAT and was told his standard score is -2. Which student has a better chance of getting admitted to college based on test score? In other words, which student did better on the exam relative to all other students who took that particular exam?

Missy

a simple random sample is drawn from a large population with a normal distribution. What is the sample distribution of the sample mean?

N(u, O/ square root of n

A statistics professor bought a new car for $35,000. For the next 5 years, she used several automotive web pages to estimate the value of the car. She then found the elast-squares regression line for data to be y=35035.71-4142.86x. The correlation coefficient was -0.99. Would it be accurate to use this equation to predict the value of the car after 10yrs?

No, because that would be extrapolation

Everytime that a student attended office hours one semester, a statistics professor asked if the student was satisfied with his teaching. Over 90% of the students said that they were satisfied with his teaching. Does this provide convincing evidence that the majority of the students in the professors class are satisifed with his teaching

No, this is an example of response bias

Nancy is curious if the consumption of sweets, mainly donuts, increases as people get older. Nancy asked 200 customers at a local Krispy Kreme how many donuts they eat in a month, y, and recorded their age, x. She obtained the following regression line y = 47 - 1.36x. What is the meaning of the slope of this regression line?

On average, the monthly consumption of donuts goes down by 1.36 for each additional increase in age (in years).

Certain private water utilities in South Carolina char a variable rate for the drinking water they provide to residences. One customer's bills over a 23-month period were used to fit a linear regression in an attempt to predict charges on future bills according to gallons consumed. The resulting regression equation is y=23.2+ 7.67x, where x is the amount of water used, in thousands of gallons and y is the predicted bill amount in dollars. Which of these choices are a correct statement resulting from this regression line?

On everage, the bill amount increased by 7.67 dollars for each additional thousand gallons consumed

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in the diet and exercise program. Researchers carefully observed the amount of weight lost five years after the study began. This study has:

One factor and three treatments

Consider two events A and B with respective probabilities P(A) and P(B). Which of the following represent the probabilities corresponding to the case where A and B are not disjoint? (Note that disjoint events have no outcomes in common.)

P(A) = 0.20, P(B) = 0.35 and P(A or B) = 0.75

To assess the opinion of students at the Ohio State University about campus safety, a reporter for the student newspaper interviews the first 15 students she met while walking on the campus late at night. The sample obtained is:

Probably biased because it was drawn using convenient sampling.

I select 2 cards from a standard deck of 52 cards and observe the color of each (26 red/black) which of the following is an appropriate sample space x for the possible outcomes?

S= {(red, red), (red, black), (black, red), (black, black)}

A small math department has 7 faculty members and 40 students. It can send six people to a national convention and they would like to send four students and two faculty members. Of the 40 students, four are selected randomly, and then two faculty members are randomly selected from the seven. This is an example of:

Stratified random sampling

The law of large numbers states that as the number of observations drawn at random from a population with finite mean μ increases, the mean of the observed values:

Tends to get closer and closer to the population mean μ

A recent article in an educational journal reports a correlation of +0.8 between math achievement and overall math aptitude. It also reports a correlation of -0.8 between math achievement and math anxiety. Which of the following interpretations is the most correct?

The correlation of +0.8 is just as strong as the correlation of -0.8

A recent survey of book critics asked 24 critics how many stars out of a possible 5 they gave to a recent novel from a popular author. The 24 critics' responses are summarized by the histogram below. Answer the following. Which of the following is correct about mean as a measure of center?

The mean is smaller than the median because the distribution is skewed to the left.

The given graph represents a population with a normal distribution. Which of the statements can we not conclude based on the graph?

The proportion of this population that lies at or below x=87 is 0.3085

An SRS of 25 recent birth records at the local hospital was selected. In the sample, the average birth weight was X ¯= 119.6 ounces. Suppose the standard deviation is known to be σ = 5.7 ounces. Assume that in the population of all babies born in this hospital, the birth weights follow a Normal distribution, with mean μ. If the sample size of birth records increases, how does the sampling distribution change?

The sampling distribution will remain Normal and the mean will remain the same regardless of the sample size, but its standard deviation will be smaller than the sampling distribution based on the smaller sample.

A UNCG instructor looked at his classes' data from his first Mid Term. He recorded the students' amount of study time (in minutes) and exam score (out of 100). He made a scatterplot and saw that it had a linear pattern. He computed correlation coefficient value or r = 0.81. After hearing about these results, one student concluded that if they study for a very long time, they will make very high test scores. What is wrong with this student's interpretation?

The student is assuming that correlation implies causation i.e. just because there is an association between a higher test score and more number of study hours, doesn't mean every student who studies for long hours will get a high score.

An instructor collected homework grades and quiz grades from students in her class. She calculated the least-squares regression line to be Quiz grade = 18.04 + 0.788*(Hw grade). What does the 18.04 represent in this equation?

The value of the quiz grade when the homework grade is 0.

The british government conducts regular surveys of household spending. The average weekly household spending on tobacco products and alcoholic beverages for each of 11 regions in Great Britain are recorded. A scatter plot of spending on tobacco versus spending on alcohol is given Which is the best interpretation of this scatterplot?

There appears to be a strong positive linear association between spending on alcohol and tobacco, except for the one possible outlier with high tobaco expenditure but low alcohol ecpenditure

A researcher obtained data from a local hospital. She found a strong positive correlation between the probability that a person will have a heart attack and their age. The researcher concluded that a lurking variable might be present. What does she mean?

There is a variable other than age that is not present in the study but affects the probability of heart attack.

Statistician WiIlliam Hammack examined the relationship between numbers of public schools in each county of Florida and the crime rate for the county. The data showed a very strong linear relationship with r=0.970. What ca we conclude from this?

There is probably a lurking variable at work

A scatterplot can be used to illustrate the relationship between: An introductory statistics class decides to investigate whether there is a relationship between the performance on midterms 1 and 2. The instructor creates a scatterplot of midterm 2 scores versus midterm 1 scores. Based on the plot which of the following is likely true?

Two quantitative variables the correlation between midterm 1 and midterm 2 scores is positive

A statistics student computes the correlation between two variables in her spreadsheet and finds r= 0.06. She concludes there is no relationship between the variables. Is she correct?

We do not have enough information to answer this question

Does the values of the standard deviation depend on the value of the mean?

Yes, because the mean must be known in oder to calculate the standard deviation

Accoriding to the National Household survey on Drug use and Health, when asked in 2012, 41% of those aged 18-24 years used cigarrettes in the past year, 9% used smokeless tobacco, 36.3% used illicit drugs and 10.4% used pain relievers or sedatives. To display this data, it would be correct to use

a bar graph but not a pie chart

A disadvantage of using a boxplot rather than a histogram is?

a boxplot shows less detail

A market researcher wants a large sample size for her survey, so she decides to stand in the food court of the mall during christmas shopping season. within the first 3 hours, she asks 150 shoppers abuot their automobile references. This is an example of

a convenience sample

in an experiment to determine if a new type of fertlizer is better than the current fertlizer 20 plots of land were randomly assigned one of the two types distance from the highway is

a lurking variable

A study attempts to determine whether a football filled with helium travels farther when kicked than one filled with air. Each subject kicked twice: once with a football filled with helium, and once with a football filled with air. The order of the type of football kicked is randomized. This is an example of

a matched pair experiment

The department of energy website contains data on 1209 model year 2016 cars and suvs. Included in the data are the engine size and combined city and highway gas mileage. Examining the data, one finds that cars with bigger engines tend to have lower gas mileages. In a scatterplot of the engine size and the gas mileage, you expect to see

a negative association

The department of motor vehicles reports that 32% of all vehicles registered in a state are made by a japanese or a european automaker, The number 32% is best described as

a parameter

a confidence interval is constructed to estimate the value of

a parameter

for which of the following situations would the central limit theroem not imply that the sample distribution for x is approximately normal?

a population is not normal, and we use samples of size n=6

Choose the correct definitions of response and explanatory variables from the list below.

a response variable measures an outcome in a statistical study. An explanatory variable explains or influences changes in the response variable

a researcher is interested in the cholesterol levels of adults in the city in which she lives. Individuals can walk in and have their cholesterol determined for free. A total of 173 people use the service, and their adverage cholesterol level is 217.8 The sample obtained is an example of

a sample probably containing bias and undercoverage

In formulatinf hypotheses for a stastical test of significance, the null hypothesis is often

a statement of "no effect of "no difference"

What is a resistant measure?

a statistic that is not affected by outliers

Jean is planning to take a foreign language class. To research how satisfied otherstudents are with their foreign language classes, she decides to take a sample of 50 students each. The university offers classes in 5 languages: spanish, japanese, russian, french and german. She will select a random sample of 10 students from each language class. Which term best describes the sampling technique Jean is using?

a stratified random sample

an assignment of probabilities to events in a sample space must obey which of the following?

all of the options are correct -they must obey the addition rule for disjoint events -they must sum to 1 when adding over all events in the sample space -the probability of any event must be a number between 0 and 1, inclusive

Researchers must be cautious wen designing web-based surveys, because these surveys are partially sensitive to

alll of the answer options are correct -nonrepsonse -undercoverage -voluntary response bias

the bars on a histogram:

always touch one other

researchers collected seeds from a certain wild plant and planted them in groups of kin. Plants grown in separate containers and non-kin plants grown in a singular container had 15% more roots. Was this a sample survey, observational study or experimetn

an experiment

The Nurses' Health Study has interviewed a sample of more than 100,000 female registered nurses every two years since 1984. The study finds that light-to-moderate drinkers had a significantly lower risk of death than either nondrinkers or heavy drinkers. The Nurses' Health Study is

an observational study

To determine if living next to a high voltage power lines increases the chances of getting cnacer researchers selected several homes at random this is

an observational study

the following graph appeared on the scholastic.com website to summarize the results of an online poll yes-379 no-1461 What percent of girls who voted in this poll that thinks cell phones should be banned?

approximately 20%

the distribution of actual weights of 8oz wedges of chedder cheese produced at a dairy is normal with mean 8.1 oz ans standard deviation 0.2 oz. A sample of 10 of these cheese wedges is selected. The distribution of the sample mean of the weights of cheese wedges is

approximately normal, with mean 8.1 and standard deviation 0.063

in an experiment to determine if a new type of fertlizer is better than the current fertlizer 20 plots of land were randomly assigned one of the two types

blocked

An administrator at a university wants to determine if there is a relationship between gender and the selected major. Assuming that the data has been collected on these variables, why would a scatterplot be inappropriate?

both variables are catagorical

Why might some decide to use a boxplot to represent a set of data rather than a histogram?

boxplots are better for side-by-side comparisons

Employees at a large company are surveyed about their health insurance status. Employees are coded as "1" if health insurance is obtained through the company's benefits program, "2" if health insurance is obtained from another source (such as through a spouse's employment benefit program), or "0" if the employee does not have health insurance. This variable is:

categorical

A political party's data bank includes the given zip codes of past donors, such as those shown in the table. 47906, 34236, 53075, 10010, 90210, 75204, 30304, 99709 Zip code is a

categorical variable

a survey of radio stations was conducted following the attacks on the world trade center in 2001. On of the variables recorded was the region the station was located in the (east, center, or west). The variable "region" is

categorical, because region is not a number

Which of the following statements is correct?

changing the units of measurement of x or y does not change the value of the correlation of r

to obtain a smaller margin of error

choose a larger sample size

to obtain a smaller margin of error

choose a smaller confidence level

If you want to examine the relationship, if any, between two categorical variables, it is best to look at the

conditional distributions

A sociologist studying freshman at a major univeristy carried out a survey, asking how often students went out per week. which strategy will privide a simple random sample?

contacting the registrar and obtaining a list of all freshman, from which a random sample will then be selected

What can be said of the correlation between the brand of a automobile and its quality?

correlation makes no sense here, because brand is a categorical variable

Which of the following best describes correlation?

correlation measures the strength of the linear relationship between two quantitative variables

Which of the following sample spaces is a legitimate possibility for the outcome of rolling a 6-sided die. The die may or may not be fair Outcomes 123456AProbability1/51/51/51/51/51/5BProbability1/31/61/61/61/61/6CProbability112112DProbability1/61/31/61/601/6EProbability1/83/802/81/83/8

Sickle-cell disease is a painful disorder of the red blood cells that in the United States affects mostly African Americans. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell disease, a study by the NIH gave the drug to 320 sickle-cell sufferers and placebo to another 320. Neither doctors nor patients were told who received the drug. The number of episodes of pain reported by each subject was recorded. This is an example of a(n):

double-blind experiment

When asked if their household financial situation is in better shape now than it was before the recession, 30% of Republicans say yes, 36% of Democrats say yes, and 32% of Independents say yes. We can display this data using

either a bar graph or pie chart

a student is chosen at random from a statistics class. Which of the following events are disjoint?

event a is that the student is a junior. Event b is that the student is a senior

a small p value for a test of significance is

evidence against the null hypothesis

Researchers investigated reasons why diff species of birds begin to sing at diff times in morning.

exmple of an expirment

Malaria is a leading cause of infectious disease and death worldwide. It is also a popular example of a vector-borne disease that could be greatly affected by the influence of climate change. The scatterplot shows total precipitation in select cities in west africa on the x-axis and the percent of people who tested positive for malaria in the select cities on the y-axis in 2013. Precipitation is which variable? The explanatory variable is sometimes referred to as the independent variable.

explanatory true

Textese is a sound based for of spelling Select an answer choice that correctly explains whether this is an observational study

explanitory : text method used response: WRAT score this is an observational study because the researchers did not assign what text methods were used by the subjects "No significant difference" means that the observed differences could be due to chance. There was no systematic difference in spelling ability among the 3 groups

A control group is always a placebo group

false

variables cannot be confounded in an experiment

false

a statistcian wishing to test a hypothesis that astudents score at most 75% on the final exam in an introductory statistics course decides to randomly select 20 students

finding the area to the left of -0.8944 and doubling it

A woman is told that her weight has a standard score of -1.5. This means that:

her weight is 1.5 standard deviations below average

a margin of error tells us

how accurate the statistic is when using it to estimate the parameter

Data were collected to determine the length a golf ball will travel when hit by a golf club at a certain speed. The speed, s, is measured in miles per hour and the length the ball travels, d, is measured in yards. The following formula gives the relationship d = 3.18 + 57.66*s. If the speed of the club hitting the ball increases by 1 mph, how does the predicted length of the ball travel change?

increase by 57.66

The Higher Education Research Institute's Freshman Survey includes more than 200,000 first-time, full-time freshman who entered college in 2015. The survey reports the following dat on the sources students use to pay for college expenses. Family resources 80.8% Student resources 53.4% Aid-not to be repaid 69% Aid-to be repaid 44.4% Select the correct explanation of why it is not correct to use a pie chart to display this data

individuals fall into more than one category

Suppose the least-squares regression line for a set of data has slope 3.2. Now suppose we remove a point from the data, compute the least-squares regression line, and find the new slope is 5.2. What do you call this point?

influential

The given scatterplot with a fitted regression line depicts total SAT scores and GPA The correlation, r, for SAT and GPA

is positive

The probability of event a is p(A)= 0.3 and the probability of event b is p(B)= 0.25. Are a and b disjoining?

it is impossible to determine from the information given

a drug manufacturer conducted a study of a new antidepreaant medication. Which of the following is true about the study?

it may have suffered from the placebo effect

a simple random sample of 1000 american adults found that the average number of hours spent watching television during a typical week was 13.8. A simple random sample of 500 canadians yeilded an average of 12. 5 hours per week of television viewing. The sampling variability associated with these sample means is

larger for the sample of Canadians, because the sample size is smaller

Which of these variables is most likely to have a normal distribution?

lengths of 100 newborns in Connecticut

If X and Y are categorical variables, one way to identify whether there is a relationship between them is to:

make a two-way table of the X and Y values

The 94 students in a statistics class are catagorized by gender and by year in school. The numbers obtained are displayed in the table. 22/94=0.234 is a value in a

marginal distribution

to compare the effectiveness of 2 detergents at removing common stains

matched pairs experiment

Which of the following measures the center of the distribution and is affected by an outlier ?

mean

The figure shows a normal curve. Find the mean of this distribution, approximated to the nearest integer

mean=1

The histogram shows the distribution of the annual hours of commuting delay per traveler for 46 small and median urban areas, fewer than one million in population. Which measure of center and variability would be most appropriate to report for this distribution?

median and quartiles

To select a sample of undergraduate students in the United States, I select a simple random sample of four states. From each of these states, I select a simple random sample of two colleges or universities. Finally, from each of these eight colleges or universities, I select a simple random sample of 10 undergraduates. My final sample consists of 80 undergraduates. This is an example of:

multistage sampling

There seems to be a clear relationship between the prevailing mortgage interest rates x and the number of new houses being built per moth in a midwestern city y over a period of 18 months. A scatterplot of the data collected shows that the linear model is appropriate. The equation of the least squares-regression line is number of new houses = 672.89-(30.65 x interest rate) and r^2=0.49. The association between the interest rate and the number of new houses is

negative

The probability of event a id p(A)=0.5 and the probability of event b is p(B)=0.7. Are a and b disjoint?

The volume of oxygen consumed (in liters per minute) while a person is at rest and while he or she is exercising (running on a treadmill) was measured for each of 50 subjects. The goal is to determine if the volume of oxygen consumed during aerobic exercise can be estimated from the amount consumed at rest. The results are plotted below.

not (1), (2)

We expect a car's highway gas mileage to be related to its city gas mileage (mpg). Data for all 2372 vehicles in the government's 2002 Fuel Economy Guide gives the regression line highway mpg = 7.68 + (1.033)*city (mpg) for predicting highway mileage from city mileage. If the percentage of variation in highway mpg explained by this regression line is 67.08%, what is the correlation coefficient?

not 1.033

For a basketball team, suppose we asked the following questions to the current players. What was your number on the jersey when you played? What is the zip code in your address? What is your height? Which variable(s) is(are) quantitative?

number on the jersey and height

which of the given is known for the p value, if a hypothesis test is significant at level a=0.05?

p-value <- 0.05

Making an expieriment double blind

reduces bias

a political party sends a mail survey to 1500 randomly selected registered voters. Of the 1500 that went out, 480 are returned and only 120 show the respondnat is stisfied.

sample is the 480 voters who returned the surveys

Most universities and colleges require an SAT score as one of the inputs to an admissions decision. If the colleges want to be able to predict college GPA based on the SAT, what would be the explanatory variable?

sat score

We need to survey a sample of the 300 passengers on a full flight from Cincinatti to London. We randomyl generate 30 seat numbers and survey the passengers who sit there. What best describes the sampling technique being used?

simple random sample

In a recent round of layoffs in a company, the percent of employees 50 and older who were laid off was much higher than the percent younger than 50 who were laid off. However, when the data were analyzed separately in each job category, the percent of employees 50 and older who were laid off was lower than the percent of employees younger than 50 who were laid off in each job category. This reversal of direction of the association between age and being laid off, when job category is taken into account, is called:

simpsons paradox

last sunday, Team a and team b played football. Team A 1. 2. 3 8. 3. 11 Team B 4. 5. 9 3. 0. 3 A reporter claimed that while team b scored more often than team a both when starting on their own side, 44% versus 33% and when starting on the opponents side, 100% versus 73%, Team a actually scored on a higher percent of their posessions, 64 This is an example of

simpsons paradox

You look at real estate ads for houses in naples florida. There are many houses ranging from $200,000 to $500,000 in price. The few houses on the water, however, have prices up to $15 million. The distribution of house prices will be

skewed to the right

Enteroliths are calcifications that form in the gut of horses. The stones can cause considerable morbidity and mortality. A study was conducted to investigate factors (such as age, diet, and environment) that may be related to the formation of enteroliths The histogram of age for the horses in the enteroliths study is

slightly right-skewed

Which statement is not true about standard deviation :

standard deviation can be negative

the four steps in a hypothesis test are

state, plan, solve, and conclude

A television station is interested in predicting whether or not voters in its listening area are in favor of federal funding for abortions. It asks its viewers to phone in and indicate whether they are in favor of or opposed to this. Of the 2241 viewers who phoned in, 70.24% were opposed to federal funding for abortions. Fill in the blank. The number 70.24% is a _

statistic

John's parents recorded his height at various ages up to 66 months. Below is a record of the results. Age (months) 36 48 54 60 66Height (inches)35 3841 43 45 John's parents decide to use the least-squares regression line of John's height on age to predict his height at age 21 years (252 months). We conclude that:

such a prediction could be misleading, because it involves extrapolation.

A sociologist wants to study the attitudes of american male college students toward marriage and husband-wife relationships. gives questionnarie to 25 of the men enrolled in sociology 101 at her college and 25 of them complete and return the questionnaire. Sample in this situation is

the 20 men who completed and returned their questionare

Which of the following measures is generally most resistant to outliers?

the IQR

the amount of roots the plant produced

continous

the amount of time a randomly selected person can hold their breath -the average number of books read in their entirety by a random sample of US adults

the average age of residents in a large residential retirement community is 69 years with standard deviation 5.8 years. A simple random sample of 100 residents is to be selected, and the sample mean age x of these residents is to be computed. We know the random varibale x has approximately a nromal distriubtion because

the central limit theorem

The california department of state police keeps track of the number of points recieved for various traffic violations by drivers. 12. 38. 50 29. 33. 27 59. 29. 23 Which distribution is displayed in the table?

the condtional distribution of premium catagory given point catagory

Your friend took an introductory statistics class last year and learned all about density curves. She tells you that two requirements of a density curve are

the curve is always above the horizontal axis, and the area under the curve is one

A university financial aid office wants to estimate how much their students typically spend on textbooks each term. It sends an email survey to 350 randomly selected students asking them to report the amount they spent on textbooks this term. What is the population of interest in this study?

the entire student body of the university

The following histogram represents the distribution of acceptance rate (percent accepted) among 20 top business school MBA programs in 2015. In each class interval, the left endpoint is included but not the right. Which statement is true

the first quartile must be at least 17.5 but less than 22.5

The histogram shows the distribution of the annual hours of commuting delay per traveler for 46 small and medium urban areas, fewer than one million in population. Which of the following must be true?

the mean is greater than the median

in the 2000 presidential election, 3 candidates split the vote as follows. Bush 47.9% Gore 48.4% Nader 2.7% We will consider a vote for al gore a success. Which of the following is correct?

the numbers 23 and 0.46 are statistics, and the number 0.484 is a parameter

in a statistical test of hypotheses, we say the data are statistically significant at level a if

the p-value is less than a

the probability distribution of a random variable is

the possible values of the random variable and the frequency with which the variable takes each value

suppose the weights of seventh-graders at a certain school vary according to a normal distribution, with a mean of 100 pounds and a standard deviation deviation of 7.5 pounds.

the probability that a random sample of students would have a mean less than or equal to 98 pounds, if the true population mean is 100 pounds

Simpsons paradox occurs if

the relationship that holds for several groups is reversed when combining all the groups

suppose you interview 10 randomly selected workers and as how many miles they commute to work. You'll compute the sample mean commute distance. Now imagine repeating the survey many, many times, each time recording a different sample mean commute distance. In the long run, a histogram of these sample means represents

the sampling distribution of the sample mean

suppose that two very large companies a and b each select random samples of their employees. Company a has 5000 employees and company b has 15000 employees. In both surveys the company will record the number of sick days taken by each emplyee. If the firm randomly selects 3% of its employees which statement is true about the sampling distribution of the sample means?

the standard deviation of the sampling distribution of the sample mean will be smaller for the larger company, company b, becauase a larger sample is being selected

discrete

the sum of the values when 2 6-sided dice are rolled -the number of tests taken in a given month by a randomly selected teenager -the number of visitors to a park on a randomly selected day in march

The five number summary of the scores on a test, in increasing order form the minimum to maximum is: 35 60 65 70 90 Based on this information:

there are both high and low suspected outliers

100 volunteers who suffer from depression are available for a study involving a new drug.A psychiatric evaluates the symptoms of all colunteers after 4 weeks to determine if there has been substantial imrpovement in ther severity of depression Which one is correct

this is an example of a completely randomized design

A sample of households in a community is selected at random from the telephone directory. In this community, 4% of households have no telephone, 10% have only cell phones and another 25% have unlisted numbers The sample will suffer from

undercoverage

Consumer reports often reviews current-model-year cars. The boxplots given can help us compare the 0 to 60 miles per hours acceleration times of cars in several categories: small, family, large, upscale, and luxury. The smaller the acceleration time the faster the car accelerates. In which category was the car with the fastest acceleration, that is, with the shortest acceleration time?

upscale

For a large lecture class, a professor decides to make his class notes available on the internet. During one of his lectures he mentions he would like some feedback. He gets comments from 23 students and most indicate that having the notes steadily available helped them in the course

voluntary response sample

A description of different houses for sale includes square footage of the house, whether or not the house has a finished basement, and the monthly electric bill. Which of the variables is categorical?

whether or not the house has a finished basement

suppose there are 3 cards in a deck: one marked with an 1, one marked with a 2 and one marked with a 5. You draw 2 cards at random without replacement.

x. 3. 6. 7 p 1/3. 1/3. 1/3`

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