Stats

For the density curve below, what percentage of the observations lies above 1.5? 75% 25% 80% 50%

25%

We have a data set where the cases are college students. One of the variables in the data set is "gender." The values of gender are 1 if the student is male and 2 if the student is female. What type of variable is gender? Quantitative and categorical Quantitative None of these answers are correct. Categorical

Categorical

Which of the following does not adequately reveal outliers? Density curves Modified boxplots Histograms Stemplots

Density curves

In a statistics class with 136 students, the professor records how much money each student has in their possession during the first class of the semester. The histogram shown below represents the data he collected. What is the range of the data set? This cannot be determined from just the histogram. 110 90 100

This cannot be determined from just the histogram.

Categorical variables are best displayed by ______. pie charts or bar graphs histograms bar graphs pie charts

pie charts or bar graphs

Quantitative variables are best displayed using _______. bar graphs pie charts or bar graphs pie charts stemplots

stemplots

The density curve below is __________. symmetric left-skewed right-skewed None of these answers are correct.

symmetric

The variable Z has a standard Normal distribution. Find the value z such that 85% of the observations fall below z. z = 0.80 z = 0.85 z = -1.04 z = 1.04

z = 1.04

The scores on a university examination are Normally distributed with a mean of 62 and a standard deviation of 11. If the bottom 5% of students will fail the course, what is the lowest mark that a student can have and still be awarded a passing grade? 57 40 62 44

44

The Insurance Institute for Highway Safety publishes data on the total damage suffered by compact automobiles in a series of controlled, low-speed collisions. The cost for a sample of nine cars, in hundreds of dollars, is provided below 10 6 8 10 4 3.5 7.5 8 9Using the correct units, what is the value of the variance? 224.85 dollars^2 38.48 dollars^2 50,555.54 dollars^2 56,875 dollars^2

56,875 dollars^2

During the early part of the 1994 baseball season, many sports fans and baseball players noticed that the number of home runs being hit seemed to be unusually large. Below are separate stemplots for the number of home runs by American League and National League teams based on the team-by-team statistics on home runs hit through Friday, June 3, 1994 (from the Columbus Dispatch, Sunday, June 5, 1994).Legend: 2|9 represents 29. What is the median for the number of home runs for the American League teams? 45 50 50.5 57.5

57.5

The following boxplot is of the birth weights (in ounces) of 160 infants born in a local hospital. The median birth weight is approximately ________________. 120 ounces 90 ounces 110 ounces 100 ounces

110 ounces

The following boxplot is of the birth weights (in ounces) of 160 infants born in a local hospital.Approximately __________ children had birth weights between 102 and 122 ounces. 100 40 50 80

80

The tails of a distribution show the _______. median None of these answers are correct. extreme values center

extremes values

The World Malaria Report (2008) has information on the number of reported malaria cases from 2005 and 2006 for the 10 countries listed in West Africa. The data are presented in the table below.The mean of the reported West African malaria cases in 2005 is ___________. greater than 1,600,000 greater than 200,000 100,000 less than 116,698

greater than 200,000

Large data sets with quantitative variables are best displayed using ________. stemplots and histograms histograms None of these answers are correct. stemplots

histograms

When drawing a histogram, it is important to make certain the mean and median are contained in the same class interval, so that the correct type of skewness can be identified. label the vertical axis so the reader can determine the counts or percentage in each class interval. have a separate class interval for each observation to get the most informative plot. make sure the heights of the bars exceed the widths of the class intervals, so that the bars are true rectangles.

label the vertical axis so the reader can determine the counts or percentage in each class interval.

Categorical variables place cases into ____ group(s). one numeric many no

many

Find the median salary. Choose the correct answer: $92,222.22 $178,333.33 $80,000.00 $55,000.00

$55,000.00

A variable is a characteristic of a ___ value. None of these answers are correct. label. case.

case

Step 1:A small accounting firm pays each of its seven clerks $55,000, three junior accountants $80,000 each, and the firm's owner $650,000.What is the mean salary paid at this firm? How many of the employees earn less than the mean? Choose the correct answer: $178,333.33, therefore ten employees earn less than the mean. $115,909.092, therefore ten employees earn less than the mean. $34,000, therefore no employees earns less than the mean. $59,444.44, therefore seven employees earn less than the mean.

$115,909.092, therefore ten employees earn less than the mean.

A consumer group surveyed the prices for cotton, extra-long twin bed sheet sets in five different department stores and reported the average price as $16.We visited four of the five stores and found the prices to be $12, $15, $17, and $22. Assuming that the consumer group is correct, what is the price of the item at the store that we did not visit? $14 $10 $17 $15

$14

This is a standard deviation contest. Which of the following sets of four numbers has the largest possible standard deviation? 0, 1, 2, 3 5, 5, 5, 5 0, 0, 10, 10 7, 8, 9, 10

0, 0, 10, 10

Consider the following data which describe the amount of time in minutes students spend studying for a quiz:10, 11, 11, 12, 12, 14, 15, 18, 19, 20, 22, 24, 39, 40, 41, 44, 46, 50, 52, 52, 53, 55, 70.What numbers make up the leaf of the first stem? 0,1,2,4,5,8,9 0,1,1,2,2,4,5,8,9 0,1,1,2,2,4,5,8,9,0,2,4,9,0,1,4,6,0,2,2,3,5,0 None of these answers are correct.

0,1,1,2,2,4,5,8,9

Chocolate bars produced by a certain machine are labeled with 8.0 ounces. The distribution of the actual weights of these chocolate bars is Normal with a mean of 8.1 ounces and a standard deviation of 0.1 ounces. A chocolate bar is considered underweight if it weighs less than 8.0 ounces. What proportion of chocolate bars weighs between 8.2 and 8.3 ounces? 0.136 0.477 0.636 0.819

0.136

Items produced by a manufacturing process are supposed to weigh 90 grams. However, there is variability in the items produced, and they do not all weigh exactly 90 grams. The distribution of weights can be approximated by a Normal distribution with a mean of 90 grams and a standard deviation of 1 gram. What percentage of the items will either weigh less than 87 grams or more than 93 grams? 0.3% 99.7% 94% 6%

0.3%

For the density curve displayed below, what is the mean? 0.75 0.25 0.71 0.50

0.50

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to -0.5 < Z < 1.2? 0.3085 0.5764 0.2815 0.8849

0.5764

The temperature at any random location in a kiln used for manufacturing bricks is Normally distributed with a mean of 1000°F and a standard deviation of 50°F. If bricks are fired at a temperature above 1125°F, they will crack and must be discarded. If the bricks are placed randomly throughout the kiln, what is the percentage of bricks that crack during the firing process? 0.62% 47.72% 49.38% 2.28%

0.62%

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to Z < 1.1? 0.1357 0.2704 0.8413 0.8643

0.8643

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to Z > -1.22? 0.8849 0.1151 0.8888 0.1112

0.8888

During the early part of the 1994 baseball season, many sports fans and baseball players noticed that the number of home runs being hit seemed to be unusually large. The numbers of home runs by American League and National League teams based on the team-by-team statistics on home runs hit through Friday, June 3, 1994, are given below (from the Columbus Dispatch, Sunday, June 5, 1994).American League35 40 43 49 51 54 57 58 58 64 68 68 75 77National League29 31 42 46 47 48 48 53 55 55 55 63 63 67The mean and standard deviation of the number of home runs hit by National League teams are 50 and 11, respectively. Suppose we wish to measure how many more home runs than last year's average of 40 these teams have had this year by subtracting 40 from each number (a team with 55 home runs has 55 - 40 = 15 more home runs than last year's average). What are the mean and standard deviation of these new numbers? 50 and -29 50 and 11 10 and -29 10 and 11

10 and 11

As part of a large ongoing study on the treatment of women with breast cancer, the treatment time (in months) of eight patients whose lymph nodes were cancer-free is recorded. Treatment time is defined as the time from the moment the cancer treatment starts until the patient is declared cancer-free.9.47 8.60 19.33 16.33 8.50 9.40 17.67 9.30What is the mean treatment time for these eight women? 11.67 months 12.325 months 10.5 months 15 months

12.325 months

The time to complete an exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7 rule, what percentage of students will complete the exam in under an hour? 5% 16% 68% 32%

16%

The first day of class the professor collects information on each student to make a data set that will be analyzed throughout the semester. The information asked includes hometown, GPA, number of classes, number of siblings, and favorite subject. How many categorical variables are in this data set? 1 2 3 4

2

The temperature at any random location in a kiln used for manufacturing bricks is Normally distributed with a mean of 1000°F and a standard deviation of 50°F. When glazed bricks are put in the oven, if the temperature is below 900°F, they will discolor. If the bricks are placed randomly throughout the kiln, what percentage of glazed bricks will discolor? 0.62% 2.28% 47.72% 49.38%

2.28%

Many states assess the skills of their students in various grades. One program that is available for this purpose is the National Assessment of Educational Progress (NAEP). One of the tests provided by the NAEP assesses the reading skills of twelfth-grade students. In a recent year, the national mean score was 285 and the standard deviation was 36 . Assuming that these scores are approximately Normally distributed, N(285 , 36 ), use the 68-95-99.7 rule to give a range of scores that includes 95% of these students. (Fill in the blanks below and enter your answers from smallest to largest.) The range is from _____ to ____ .

213 to 357

The Michigan Department of Transportation (M-DOT) is working on a major project: 80% of the highways in Michigan need to be repaved. To speed completion of this project, many contractors will be working for M-DOT. Contractors are currently bidding on the next part of the project. To help make a decision about which contractor to hire, M-DOT collects many variables besides just the estimated cost. One of those variables is the contractor's estimate of the number of workdays required to finish the job. Twenty contractors have bid on the next job. The boxplot below represents their estimates of the number of work days required. What is (approximately) the interquartile range, based on the boxplot? 360 days 140 days 270 days 760 days

270 days

The first day of class, the Professor collects information on each student to make a data set that will be analyzed throughout the semester. The information asked includes; hometown, GPA, number of classes taking, number of siblings, and favorite subject. How many quantitative variables are in this data set? 5 3 1 2

3

Many states assess the skills of their students in various grades. One program that is available for this purpose is the National Assessment of Educational Progress (NAEP). One of the tests provided by the NAEP assesses the reading skills of twelfth-grade students. In a recent year, the national mean score was 285 and the standard deviation was 37 . Assume that these scores are approximately Normally distributed, N(285 , 37 ). How high a score is needed to be in the top 25 % of students who take this exam (use technology and give your answer as a whole number)?

310

. High-density lipoprotein (HDL) is sometimes called the "good cholesterol" because high values are associated with a lower risk of heart disease. According to the American Heart Association, people over the age of 20 years should have at least 40 mg/dL of HDL cholesterol. HDL cholesterol levels for men have a mean of 46 mg/dL with a standard deviation of 13.6 mg/dL. Assume that the distribution is Normal. Men with more than 40 mg / dL but less than 60 mg / dL of HDL are in the intermediate Men with more than 40 mg / dL but less than 60 mg / dL of HDL are in the intermediate range neither very good or very bad. What proportion are in this category? range neither very good or very bad. What proportion are in this category? (Fill in the blank below and round your answer to a whole number.) ___% of men are in the intermediate range.

33%

For the density curve below, what percentage of the observations lies between 0.5 and 1.2? 35% 50% 25% 70%

35%

The preparation time to mail envelopes with a weekly report to all executives in a company has a Normal distribution with a mean of 35 minutes and a standard deviation of 2 minutes. On 95% of such occasions, the mailing preparation takes less than x minutes. What is the value of x? 31.71 34.75 35.25 38.29

38.29

In a statistics class with 136 students, the professor records how much money each student has in their possession during the first class of the semester. The histogram shown below represents the data he collected. What is approximately the percentage of students with under $10 in their possession? 35% 40% 44% 50%

44%

In a statistics class with 136 students, the professor records how much money each student has in their possession during the first class of the semester. The histogram shown below represents the data he collected.What is approximately the percentage of students with under $10 in their possession? 50% 35% 44% 40%

44%

The Environmental Protection Agency records data on the fuel economy of many different makes of cars. Data on the mileage of 20 randomly selected cars are listed below. The values are ordered for convenience. What is the interquartile range for the mileage data? 17 miles per gallon 8.5 miles per gallon 16.5 miles per gallon 25 miles per gallon

8.5 miles per gallon

The number of Facebook friends students at a university have are Normally distributed with a mean of 1200 and a standard deviation of 200. What percentage of students has at least 1000 Facebook friends? 84.13% 15.86% 42.07% None of these answers are correct.

84.13%

A well-known maker of jams and jellies packages its jams in jars labeled "250 milliliters." The process used to fill the jars is known to dispense an amount of jam that is a Normally distributed variable with μ = 252 milliliters and σ = 0.9 milliliters. What percentage of jars will be filled with between 251 milliliters and 254 milliliters? 85.3% 14.7% 8.5% 13.4% 1.3%

85.3%

Many residents of suburban neighborhoods own more than one car but consider one of their cars to be the main family vehicle. The age of these family vehicles can be modeled by a Normal distribution with a mean of 2 years and a standard deviation of 6 months. What percentage of family vehicles is between 1 and 3 years old? 68% This cannot be determined based on the information given. 99.7% 95%

95%

The Insurance Institute for Highway Safety publishes data on the total damage suffered by compact automobiles in a series of controlled, low-speed collisions. The cost for a sample of nine cars, in hundreds of dollars, is provided below10 6 8 10 4 3.5 7.5 8 9What is the interquartile range of the above data? A value less than $200 A value between $460 and $800 A value between $200 and $460 None of these answers are correct.

A value between $200 and $460

A description of different houses on the market includes the following three variables. Which of these variables is quantitative? The monthly electric bill The monthly gas bill All of the answers are correct. The square footage of the house

All of the answers are correct.

The appearance of a histogram will change when you _______. change the class size add more data All of these answers are correct. remove outliers

All of these answers are correct.

The following stemplot displays the number of forest fires (in thousands) that occurred each year over the period from 1970 to 2000 in Canada, where 5|2 represents 5200 fires. From the stemplot we can see that the shape of the distribution is skewed to the left. there appears to be one large peak. there was a total of 9 years in which more than 10,000 fires occurred. only one year had fewer than 6000 fires. All of these answers are correct.

All of these answers are correct.

When examining a distribution of a quantitative variable, which of the following features do we look for? Overall shape, center, and spread Symmetry or skewness Deviations from overall patterns such as outliers The number of peaks or modes All of these answers are correct.

All of these answers are correct.

When examining a distribution of a quantitative variable, which of the following features do we look for? All of these answers are correct. The number of peaks or modes Deviations from overall patterns such as outliers Symmetry or skewness Overall shape, center, and spread

All of these answers are correct.

Which of the following statements about the standardized z-score of a value of a variable X, which has a mean of m and a standard deviation of s, is/are TRUE? The z-score tells us how many standard deviation units from the original observation fall away from the mean. The z-score has a mean equal to 0. All of these statements about the z-score are true. The z-score has a standard deviation equal to 1. The z-score tells us the direction the observation falls away from the mean.

All of these statements about the z-score are true.

Malaria is a leading cause of infectious disease and death worldwide. The table below represents the mean number of reported malaria cases (between 1996 and 2006) for each of 10 West African countries, as published in the journal Statistica Neerlandica in 2010.What is the best method to display these data? Stem-and-leaf plot Histogram Bar graph Pie chart

Bar graph

When using a histogram to display categorical values, you should make sure the categories are in alphabetical order. True—histograms are not useful if the categories are not in order. True—histograms can be used on any type of data. False—You cannot use histograms to display categorical data. False—The categories cannot be in alphabetical order when displaying categorical data.

False—You cannot use histograms to display categorical data.

The histogram below shows data from 30 students who were asked, "How much time do you spend on the Internet in minutes?" How could you improve the histogram to better display the distribution? Do nothing—the histogram is appropriate. Add two more data points. Increase the class size. Decrease the class size.

Increase the class size

According to the Bureau of Labor and Statistics in 2014, the average salary of all female workers is $37,596. The average salary of all male workers is $45,500.What must be true about the average salary of all workers? It must be $38,000. None of these answers are correct. It must be larger than the median salary. It could be any number between $37,596 and $45,500.

It could be any number between $37,596 and $45,500

The ages (to the nearest year) of the 667 people participating in a large workshop are summarized as shown below. What is true about the median age? It must be 21. It must be over 21. It must be 20. It could be any number between 19 and 20.

It must be 20.

Twenty professional athletes were asked, "What age did you graduate from college?" The responses are displayed in the histogram below. Does the distribution appear to be symmetric? Can't tell No Yes

No

The Insurance Institute for Highway Safety publishes data on the total damage suffered by compact automobiles in a series of controlled, low-speed collisions. The cost for a sample of nine cars, in hundreds of dollars, is provided below 10 6 8 10 4 3.5 7.5 8 9 What is the first quartile for the above data? $350 $500 $600 None of these answers are correct.

None of these answers are correct.

The asking prices (in thousands of dollars) for a sample of 13 houses currently on the market in Neighborville are listed below. For convenience, the data have been ordered.175 199 205 234 259 275 299 304 317 345 355 384 549What is the five-number summary? None of these answers are correct. 175 219.5 299 350 384 199 219.5 299 350 549 175 234 299 331 549

None of these answers are correct.

The asking prices (in thousands of dollars) for a sample of 13 houses currently on the market in Neighborville are listed below. For convenience, the data have been ordered.175 199 205 234 259 275 299 304 317 345 355 384 549Use the 1.5 × IQR rule to determine if there are any outliers present. What is/are the value(s) of the outlier(s)? One outlier: 175 There are no outliers present. Two outliers: 175 and 549 One outlier: 549

One outlier: 549

At a Canadian agricultural fair held in Neguac, New Brunswick, giant pumpkins were entered into a competition. The following stem-and-leaf plot of the weight (in pounds) of the 35 pumpkins in the competition was constructed, where, for example, 9|4 represents 940 pounds. The quartiles, Q1 and Q3, for these data are Q1 = 490 and Q3 = 660. Q1 = 320 and Q3 = 640. Q1 = 322 and Q3 = 716. Q1 = 320 and Q3 = 660. Q1 = 90 and Q3 = 1190.

Q1 = 320 and Q3 = 660

The units of measurement are an important part of the description of what type of variables? Categorical Quantitative None of these answers are correct. Quantitative and categorical

Quantitative

We have a data set where the cases are college students. One of the variables in the data set is "age of the student." What type of variable is age of the student? Quantitative Quantitative and categorical None of these answers are correct. Categorical

Quantitative

We have a data set where the cases are college students. One of the variables in the data set is "age of the student." What type of variable is age of the student? Quantitative and categorical None of these answers are correct. Categorical Quantitative

Quantitative

In a statistics class with 136 students, the professor records how much money each student has in their possession during the first class of the semester. The histogram shown below represents the data he collected. Which of the following description(s) is/are correct regarding the shape of the histogram? Skewed right Skewed left Symmetric An outlier is present. Unimodal Bimodal

Skewed right An outlier is present. Unimodal

The salaries of Major League Baseball players range from several hundred thousand dollars per year to many millions per year. Suppose a histogram is made of all last year's salaries of Major League Baseball players. Which shape would best describe the shape of this histogram? Bimodal Skewed to the right Skewed to the left Bell-shaped

Skewed to the right

A sample of employees of a large pharmaceutical company has been obtained. The length of time (in months) they have worked for the company was recorded for each employee. A stemplot of these data is shown below. In the stemplot 6|2 represents 62 months .What would be a better way to represent this data set? Display the data in a time plot. Display the data in a boxplot. Split the stems. Use a histogram with class width equal to 10.

Split the stems

The first day of class the professor collects information on each student to make a data set that will be analyzed throughout the semester. The information asked includes hometown, GPA, number of classes, number of siblings, and favorite subject. What are the cases in this data set? The semester The professor The college students None of these answers are correct.

The college students

Researchers are conducting a state-wide survey for the U.S. Postal Service. The survey records many different variables of interest. Which of the following variables is categorical? The number of people, both adults and children, living in the household The county of residence The age of the respondent The total household income, before taxes, in 2010

The county of residence

In a statistics class with 136 students, the professor records how much money each student has in their possession during the first class of the semester. The histogram shown below represents the data he collected. From the histogram, which of the following is TRUE? The mean and median are approximately equal. It is impossible to compare the mean and median for these data. The mean is smaller than the median. The mean is larger than the median.

The mean is larger than the median.

For the density curve below, which one of the following is TRUE? The mean and median are equal. The mean could be either greater than or less than the median. The mean is greater than the median. The mean is less than the median.

The mean is less than the median.

There are three children aged three, four, and five in a room. If another four-year-old child enters the room, what will happen to the mean and variance? The mean will stay the same, but the variance will decrease. The mean and variance will both decrease. The mean and variance will both stay the same. The mean will stay the same, but the variance will increase.

The mean will stay the same, but the variance will decrease

Which one of the following statements about the mean and the median of a density curve is FALSE? The median and the mean have the same value if the density curve is symmetric. The median of a skewed density curve is pulled away from the mean in the direction of the long tail. The median is the point on the axis that divides the area under the density curve in two equal halves. The mean is the "balance point" of the density curve. For a symmetric density curve, both the mean and the median are at the center of the curve

The median of a skewed density curve is pulled away from the mean in the direction of the long tail.

The New England Patriots are a top-ranked team in the National Football League and the Saskatchewan Roughriders are the 2007 champions of the Canadian Football League. From the 2007 rosters of these two teams, the weight of each player was determined and the following side-by-side boxplots of their weights is provided below. Which of the following statements about these side-by-side boxplots is/are TRUE? The weights of the New England team exhibit less overall variation than the Saskatchewan team. The IQR for the Saskatchewan team is greater than the IQR of the New England team. The median weight for the New England team is higher than the median weight for the Saskatchewan team.

The median weight for the New England team is higher than the median weight for the Saskatchewan team.

Which of the following is likely to have a mean that is smaller than the median? The number of text messages sent by students and faculty at a large university The scores of students (out of 100 points) on a very difficult exam on which most score poorly but a few do very well The scores of students (out of 100 points) on a very easy exam in which most score perfectly but a few do very poorly The salaries of all National Football League players

The scores of students (out of 100 points) on a very easy exam in which most score perfectly but a few do very poorly

The standard deviation s is a useful measure of a characteristic of a distribution of data values. Which of the following statements about s is FALSE? The standard deviation can never be zero. As the data values become more spread out about their mean, s becomes larger. The standard deviation measures the spread of the data around the mean. The standard deviation is appropriate as a measure of spread when the mean is chosen as the measure of center. The standard deviation is not resistant; a few outliers can make s very large.

The standard deviation can never be zero.

A type of variable where arithmetic operations do not make sense are called _______. categorical cases distributions quantitative

categorical

A nationwide study was done to assess the programming proficiency of students taking a statistical programming class. The students were asked their proficiency in the statistical software SAS. The survey was sent to students at over 100 universities and 112 responses were received from 21 different universities. The results were published in the journal International Mathematical Forum in 2011. The results in the form of a pie chart are shown below.From the pie chart, we can see that most students are _____. not proficient at all very proficient somewhat proficient

somewhat proficient

Agricultural fairs often hold competitions for produce grown by local gardeners. The following data are the weight (in pounds) of tomatoes entered into an annual fair in Roland, Manitoba, Canada, in 2007.2.48 1.52 1.15 1.13 1.00 0.99 0.96 0.94 0.75Apply the 1.5 × IQR rule to the data to check for outlier values. In this case, _____________. the values 1.52 and 2.48 are both outliers the value 2.48 is the only outlier there are no outliers the value 0.75 is the only outlier the values 0.75 and 2.48 are both outliers

the value 2.48 is the only outlier

Statistics were gathered on the number of homicides committed with guns in Australia in the years from 1980 to 2004.From these data the following graph was constructed. This plot is a graph of a(n) _____________, and it shows that there is/are ___________ in the data. line; an increasing trend histogram; multiple peaks time series; a decreasing trend categorical variable; skewness to the right quantitative variable; outlier values

time series; a decreasing trend

Many states assess the skills of their students in various grades. One program that is available for this purpose is the National Assessment of Educational Progress (NAEP). One of the tests provided by the NAEP assesses the reading skills of twelfth-grade students. In a recent year, the national mean score was 290 and the standard deviation was 38 . Assume that these scores are approximately Normally distributed, N(290 , 38 ). Give the z-score ( ±±0.01) for a student who received a score of 320 .

z = .79