AP Statistics FINAL study guide

A news release for a diet products company reports: "there's good news for the 65 million americans currently on a diet." its studies showed that people who lose weight can keep it off. The sample was twenty graduates of the company's program who endorse it in commercials. The results of the study are probably: 1. biased, understating the effectiveness of the diet 2. biased, but it is hard to tell whether the results will overstate or understate the effects of the diet 3. Biased, overstating the effectiveness of the diet 4. unbiased because these are nationally recognized individuals 5. unbiased, but they could have been more accurate. A large sample size should be used

Biased, overstating the effectiveness of the diet

I select two cards from a deck of 52 cards and observe the color of each (26 cards in the deck are red and 26 are black). Which of the following is an appropriate sample space S for the possible outcomes? 1. S = {red, black} 2. S = {(red, red), (red, black), (black red), (black, black)}, where for example, (red, red) stands for the event "the first card is red and the second card is red. 3. S = {(red, red), (red, black), (black, black)}, where for example, (red, red) stands for the event "the first card is red and the second card is red. 4. S = {0, 1, 2} 5. All of the above

S = {(red, red), (red, black), (black red), (black, black)}, where for example, (red, red) stands for the event "the first card is red and the second card is red.

Scenario 5-7. The probability of a randomly selected adult having a rare disease for which a diagnostic test has been developed is 0.001. The diagnostic test is not perfect. The probability the test will be positive (indicating that the person has the disease) is 0.99 for a person with the disease and 0.02 for a person without the disease. Using Scenario 5-7. If a randomly selected person is tested and the result is positive, the probability the individual has the disease is: 1) 0.001 2) 0.047 3) 0.019 4) 0.021 5) 0.020

0.047

A review of voter registration records in a small town yielded the following table of the number of males and females registered as democrat, republican, or some other affiliation Male Female Total Democrat 300 600 900 Republican 500 300 800 Other 200 100 300 Total 1000 1000 2000 1) 300 2) 0.15 3) 30 4) 0.30 5) 0.33

0.30

Scenario 5-11. The following table compares the hand dominance of 200 Canadian high-school students and what methods they prefer to communicate with their friends. cell phone/text in person online Total left 12 13 9 34 right 43 72 51 166 total 55 85 60 200 Suppose one student is chosen randomly from this group of 200. Use Scenario 5-11. If you know the person that has been randomly selected is left-handed, what is the probability that they prefer to communicate with friends in person? 1) 0.065 2) 0.153 3) 0.17 4) 0.382 5) 0.53

0.382

Scenario 5-11. The following table compares the hand dominance of 200 Canadian high-school students and what methods they prefer to communicate with their friends. cell phone/text in person online Total left 12 13 9 34 right 43 72 51 166 total 55 85 60 200 Suppose one student is chosen randomly from this group of 200. Use Scenario 5-11. What is the probability that the student chosen is left-handed or prefers to communicate with friends in person. 1) 0.17 2) 0.595 3) 0.53 4) 0.065 5) 0.425

0.53

Below is a scatter plot (with the least squares regression line) for calories and proteins (in grams) in one cup of 11 varieties of dried beans. The computer for this regression is below the plot. Use scenario 3-7. Which of the following statements is a correct interpretation of the slope of the regression line? 1. For each 1-gram increase in the calorie content, the predicted protein content increases by 2.08 grams. 2.For each 1-unit increase in the calorie content, the predicted protein content increases by 2.08 grams. 3. For each 1-unit increase in the calorie content, the predicted protein content increases by 0.063 grams. 4. For each 1-gram increase in the protein content, the predicted calorie content increases by 0.063 grams. 5. For each 1-gram increase in the protein content, the predicted calorie content increases by 0.024 grams.

3. For each 1-unit increase in the calorie content, the predicted protein content increases by 0.063 grams.

You want to use simulation to estimate the probability of getting exactly one head and one tail in two tosses of a fair coin. You assign the digits 0, 1, 2, 3, 4 to heads and 5, 6, 7, 8, 9 to tails. Using the following random digits to execute as many simulations as possible, what is your estimate of the probability? 19226 95034 05756 07118 1. 1/20 2. 1/20 3. 5/10 4. 6/10 5. 2/3

6/10

The 35th percentile of a population is the number X such that 1. 35% of the population scores are above X 2. 65% of the populations scores are above X 3. 35% of the population scorese equal X 4. X is 35% of the population median 5. X is 35% if the population mean

65% of the population scores are above X

The time to complete a standardized exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given? 1) 61.6 minutes 2) 78.4 minutes 3) 84 minutes 4) 79.8 minutes 5) 92.8 minutes

78.4 minutes

Scenario 4-1. A sports writer wants to know how strongly lafayette residents support the local minor league baseball team, the Lafayette Leopards. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium. Use scenario 4-1. The newspaper asks you to comment on their survey of local opinion. You say: 1. This is a simple random sample. it gives very accurate results 2. this is a simple random sample. the results are not biased, but the sample is too small to have high precision 3. this is a census, because all fans had a chance to be asked 4.This is a convenience sample. It will almost certainly overestimate the level of support among all Lafayette residents. 5.This is a convenience sample. It will almost certainly underestimate the level of support among all Lafayette residents.

This is a convenience sample. It will almost certainly overestimate the level of support among all Lafayette residents.

Suppose there are three cards in a deck, one marked with a 1, and one marked with a 5. You draw two cards at random and without replacement from the deck of three cards. The sample space S = {(1, 2), (1, 5), (2, 5)} consists of these three equally likely outcomes. Let X be the sum of the numbers on the two cards drawn. Which of the following is the correct set of probabilities for X? 1. X P(X) 1 1/3 2 1/3 5 1/3 2. X P(X) 3 1/4 6 1/2 7 1/2 3. X P(X) 3 1/3 6 1/3 7 1/3 4. X P(X) 1 1/4 2 1/2 5 1/2 5. X P(X) 3 3/16 6 6/16 7 7/16

X P(X) 3 1/3 6 1/3 7 1/3

A stratified random sample addresses the same issues as which of the following experimental designs? 1. a block design 2. a double-blind experiment 3. an experiment with a placebo 4. a completely randomized design 5. a confounded, nonrandomized study

a block design

The principle reason for the use of random assignment in designing experiments is that it: 1. distinguishes a treatment effect from the effects of confounding variables 2. allows double-blinding 3. reduces sampling variability 4. creates approximately equal groups for comparison 5. eliminates the placebo effect

creates approximately equal groups for comparison

Scenario 5-3. Ignoring twins and other multiple births, assume that babies born at a hospital are independent random events with the probability that a baby is a boy and the probability that a baby is a girl both equal 0.5. Using Scenario 5-3. The events A = the next two babies are boys, and B = the next two babies are girls are: 1) conditional 2) complementary 3) independent 4) disjoint 5) none of the above

disjoint

The principle reason for the use of controls in designing experiments is that it: 1. distinguishes a treatment effect from the effects of confounding variables. 2. allows double-blinding 3. reduces sampling variability 4. creates approximately equal groups for comparison 5. eliminates the placebo effect

distinguishes a treatment effect from the effects of confounding variables.

In order to assess the effects of exercise on reducing cholesterol, a researcher took a random sample of fifty people from a local gym who exercised regularly and another random sample of fifty people from the surrounding community who did not exercise regularly. They all reported to a clinic to have their cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of whether or not subjects exercised regularly. Use Scenario 4-5. This is a(n): 1. observational study 2. experiment, but not a double blind experiment 3. double blind experiment 4. matched pairs experiment 5. block design

double blind experiment

Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before a mid-term exam. Use Scenario 4-6. The response variable in this study is: 1. two cups of coffee 2. the time the class is held 3. class attendance 4. teacher's performance 5. exam performance

exam performance

A standard score describes 1. how much skew there is in a distribution 2. how much spread there is in a distribution 3. how far apart the mean and the median of a distribution are 4. how far a particular score is from the mean 5. how far a particular score is from the median

how far a particular score is from the mean

Scenario 2-1 A sample was taken of the salaries of 20 employees of a large company. The following are the salaries (in thousands of dollars) for this year. For convenience, the data are ordered: 28 31 34 35 37 41 42 42 42 47 49 51 52 52 60 61 67 72 75 77 Suppose each employee in the company receives a $3,000 raise for next year 1. increase by √(3000) 2. be unchanged 3. be multiplied by 3,000 4. increase by 3,000 5. increase by 150

increase by $3,000

The height (in feet) and volume (in cubic feet) of usable lumber of 32 cherry trees are measured by a researcher. The goal is to determine if volume of usable lumber can be estimated from the highest of a tree Using scenario 3-1. If the data point (65, 70) were removed from this study, how would the value of the correlation r change? 1. r would not change, since it's value does not depend on which variable is used for X and which is used for Y 2. r would would be larger, since this point does not fall in the pattern of the rest of the data. 3. r would be smaller, because this point falls in the pattern of the rest of the data 4. r would be smaller, since there are fewer data points 5. r would would be larger, since X and Y coordinates are larger than the mean X nad mean Y, respectively.

r would would be larger, since this point does not fall in the pattern of the rest of the data.

Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before a mid-term exam. Use Scenario 4-6. Suppose half of the 8:30 students are randomly allocated to the treatment group (two cups of coffee), the other half to the control group (two cups of decaf). In addition, half of the 9:30 students are randomly allocated to the treatment group, the other half to the control group This is an example of a: 1. voluntary response study 2. stratified sampling procedure 3. matched pairs design 4. completely randomized design 5. randomized block design

randomized block design

The Bradley effect is a theory proposed to explain observed discrepancies between voter opinion polls and election outcomes in some elections where a white candidate and a non-white candidate run against each other.The theory proposes that some voters tend to tell pollsters that they are undecided or likely to vote for a non-white candidate, and yet, on election day, vote for the white opponent. This is an example of: 1. voluntary response bias 2. bias resulting from question wording 3. undercoverage 4. nonresponse 5. response bias

response bias

A public opinion in Ohio wants to determine whether or not registered voters in the state approve of a measure to ban smoking in all public areas. They select a simple random sample of fifty registered voters from each county in the state and ask whether they approve or disapprove of the measure. This is an example of a: 1. systematic random sample. 2. stratified random sample. 3. multistage sample. 4. simple random sample. 5. cluster sample.

stratified random sample

Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before a mid-term exam. Use Scenario 4-6. Instead of giving all students in the 8:30 section two cups of coffee, students in the 8:30 section are randomly assigned to a treatment group (two cups of coffee) or control group (two cups of decaffeinated coffee). The coffee is so bad that students cannot tell whether they are in the treatment or the control group. As it turns out, students in both groups do better on the exam than students in the 9:30 section, who weren't given anything. This ould be the result of: 1. the placebo effect 2. an observational study 3. voluntary response 4. sampling variability 5. all of the above

the placebo effect

A 1992 Roper poll found that 22% of Americans say that the Holocaust may not have happened. The actual question asked in the poll was "Does is seem possible or impossible to you that the Nazi extermination of the Jews never happened?" and 22% responded possible. The results of this poll cannot be trusted because: 1. undercoverage is present. Obviously, those people who did not survive the Holocaust could not be in the poll. 2. the question is worded in a confusing manner. 3. we do not know who conducted the poll or who paid for the results. 4. nonresponse is present. Many people will refuse to participate, and those who do will be biased in their opinions. 5. the question is clearly biased in the direction of a "possible" answer.

the question is worded in a confusing manner

The collection of all possible outcomes of a random phenomenon is called: 1. a census 2. the probability 3. the distribution 4. a change experiment 5. the sample space

the sample space

The bar graph below summarizes responses of dog owners to the question, "Where in the car do you let your dog ride?" 1. Each owner gave only one answer to the question 2. These data could also be presented in a pie chart 3. a majority of owners do not allow their pets to ride in the front passenger seat 4. the vertical scale of this graph exaggerates the difference between the percentage who let their dogs ride in the driver's lap versus a passenger's lap 5. roughly twice as many pets are allowed to sit in the front passenger seat as in the passenger's lap

the vertical scale of this graph exaggerates the difference between the percentage who let their dogs ride in the driver's lap versus a passenger's lap

Scenario 3-1, the height (in feet) and volume (in cubic feet) of usable lumber of 32 cherry trees are measured by a researcher. The goal is to determine if volume of usable lumber can be estimated from the highest of a tree. In this study, the response variable is: 1. height of researcher 2. impossible to determine 3. the measuring instrument used to measure volume 4. volume of lumber 5. height of tree

volume of lumber

Suppose that A and B are independent events with P(A) = 0.2 and P (B) = 0.4 P (A n B^c) is 1) 0.60 2) 0.08 3) 0.40 4) 0.52 5) 0.12

0.12

Consider the following cumulative relative frequency graph of the scores of students in an introductory statistics course: A grade of C or C+ is assigned to a student who scores between 55 and 70. the percentage of students who obtained a grade of C or C+ is? 1) 15% 2) 50% 3) 20% 4) 30% 5) 25%

20%

In a certain town, 60% if the households have fiber optic internet access, 30% have at least one high-definition television, and 20% have both. The proportion of households that have neither fiber optic internet or high-definition television is: 1) 10% 2) 0% 3) 90% 4) 30% 5) 80%

30%

Below is a histogram of the heights of gold-medal winning high jumps in the olympic games since 1896. Which of the following values is closest to the mean jump? 1. 70 inches 2. 74 inches 3. 75 inches 4. 86 inches 5. 81 inches

81 inches

A study gathers data on the outside temperature during the winter, in degrees Fahrenheit, and the amount of natural gas a household consumes, in cubic feet per day. Call the temperature x and gas consumption y. The house is heated with gas, so x helps explain y. The least-squares regression line for predicting y from x is y = 1344 - 19x Use Scenario 3-9. On a day when the temperature is 20 degrees F, the regression line predicts that gas used will be about 1. 1724 cubic feet 2. 1383 cubic feet 3. none of these 4. 1325 cubic feet 5. 964 cubic feet

964 cubic feet

Scenario 4-1. A sports writer wants to know how strongly lafayette residents support the local minor league baseball team, the Lafayette Leopards. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium. Use scenario 4-1. The intended population for this survey is 1. all people attending the game the day the survey was conducted 2. all leopards fans 3. al residents of lafayette 4. the 20 people who gave the sportswriter their opinion 5. all american adults

All residents of Lafayette

We wish to choose a simple random sample of size three from the following employees of a small company. To do this, we will use the numerical labels attached to the names below. 1. Bechhofer 4. Kesten 7. Taylor 2. Brown 5. Kiefer 8. Wald 3. Ito 6. Spitzer 9. Weiss We will also use the following list of random digits, reading the list from left to right, starting at the beginning of the list. 11793 20495 05907 11384 44982 20751 37498 Using Scenario 4-3. The simple random sample is: 1. 117 2. Bechhofer, Bechhofer again, and taylor 3. Kesten, Kiefer, Taylor 4.Bechhofer, Taylor, Weiss 5. Taylor, Weiss, Ito

Bechhofer, Taylor, Weiss

Which of the following is NOT a major principle of good design for all experiments? 1. Comparison to a control. 2. Replication 3. Blocking 4. Randomization 5. All of these are important principles for every experiment.

Blocking

A policeman records the speeds of cars on a certain section of roadway with a radar gun. The histogram below shows the distribution of speeds for 251 cars. Which of the following measures of center and spread would be the best ones to use when summarizing these data? 1. mean and interquartile range 2. median and standard deviation 3. median and interquartile range 4. median and range 5. mean and standard deviation

Mean and Standard Deviation

Which of the following are most likely to be negatively correlated? 1. the total floor space and the price of an apartment in new york 2. the percentage of body fat and the time it takes to run a mile for male college students 3. the heights and yearly earnings among 35-year-old U.S. adults 4. gender and yearly earnings among 35-year-old U.S. adults 5. the prices and weights of all bicycles sold last year in chicago

The prices and the weights of all racing bicycles sold last year in Chicago.

You open a package of M & M candies and count how many there are if each color. The distribution of the variable "candy color" is: 1. The colors: red, orange, green, yellow, brown, blue 2. The total number of candies in the package 3. six---the number of different colors there are in the package 4. the six different colors and how many there are of each 5. since "color" is categorical variable, it doesn't have a distribution

The six different colors and how many there are of each

Which of the following is true of the correlation r? 1. it is a resistant measure of association 2. if r is the correlation between X and Y, then -r is the correlation between Y and X 3. -1 < r < 1 4. whenever all the data lie on a perfectly straight line, the correlation r will always be equal to +1.0 5. all of the above

-1 < r < 1

Event A has probability 0.4. Event B has probability 0.5. If A and B are disjoint, then the probability that both events occur is 1) 0.9 2) 0.2 3) 0.7 4) 0.0 5) 0.1

0.0

Scenario 5-7. The probability of a randomly selected adult having a rare disease for which a diagnostic test has been developed is 0.001. The diagnostic test is not perfect. The probability the test will be positive (indicating that the person has the disease) is 0.99 for a person with the disease and 0.02 for a person without the disease. Using Scenario 5-7. The proportion of adults for which the test would be positive is 1) 0.00002 2) 0.00099 3) 0.01998 4) 0.02097 5) 0.02100

0.02097

Scenario 5-3. Ignoring twins and other multiple births, assume that babies born at a hospital are independent random events with the probability that a baby is a boy and the probability that a baby is a girl both equal 0.5. Using Scenario 5-3. The probability that the next five babies are girls is: 1) 0.0625 2) 1.0 3) 0.03125 4) 0.1 5) 0.5

0.03125

Scenario 1-6. A sample was taken of the salaries of 20 employees of a large company. The following boxplot shows the salaries (in thousands of dollars) for this year. Use Scenario 1-6. Based on the boxplot, which of the following statements is true? 1. the maximum salary is between 60,000 and 70,000 2. the minimum salary is 20,000 3. the range of the middle half of the salaries is about 20,000 4. the median salary is about 40,000 5. 25% of the employees make more than 70,000

the range of the middle half of the salaries is about 20,000

Using the standard Normal distribution tables, the area under the standard Normal curve corresponding to -0.5 < Z < 1.2 is 1) 0.2815 2) 0.3085 3) 0.5764 4) 0.3661 5) 0.8849

0.5764

Scenario 5-3. Ignoring twins and other multiple births, assume that babies born at a hospital are independent random events with the probability that a baby is a boy and the probability that a baby is a girl both equal 0.5. Using Scenario 5-3. The probability that at least one of the next three babies is a boy is: 1) 0.875 2) 0.125 3) 0.667 4) 0.750 5) 0.333

0.875

Scenario 1-6. A sample was taken of the salaries of 20 employees of a large company. The following boxplot shows the salaries (in thousands of dollars) for this year. Use Scenario 1-6. Based on the boxplot, the five-number summary is? 1) 28, 41, 48, 58, 77 2) 28, 39, 48, 60.5, 77 3) 28, 30, 51, 58, 77 4) 28, 41, 51, 60.5, 7 5) 26, 39, 48, 60.5, 81

28, 39, 48, 60.5, 77

If the heights of 99.7% of American men are between 5' 0" and 7' 0", what is your estimate of the standard deviation of the height of American men? 1) 4'' 2) 1'' 3) 3'' 4) 6'' 5) 12''

4''

The five-number summary of the distribution of scores on the final exam in psych 001 last semester was: 18 39 62 76 100. Which of the following best describes the location of the 80th percentile? 1. between 76 and 100 2. 76 3. between 18 and 39 4. between 62 and 76 5. probably between 39 and 76, since most of the class scored between these two numbers

Between 76 and 100

Scenario 3-2. The following table and scatter plot present data on wine consumption (in liters per person per year) and death rate from heart attacks (in death per 100,00 people per year) in 19 developed Western countries. Using scenario 3-2. Which country is represented by the clear triangle in the scatter plot? 1. New Zealand 2. Canada 3. Finland 4. Belgium 5. Italy

Canada

A fisheries biologist studying whitefish in a canadian lake collected data on the length (in cm) and egg production for 25 female fish. A scatterplot of her results and computer regression analysis of egg production versus fish length are given below. Use Scenario 3-8. The equation of the least-squares regression line is 1. Eggs = -142.74 + 39.25 (Length) 2. Eggs = 39.25 - 142.74 (Length) 3. Eggs = 25.55 + 5.392 (Length) 4. Length = 25.55 + 5.392 (Eggs) 5. Length = -142.74 + 39.25 (Eggs)

Eggs = -142.74 + 39.25 (Length)

Below is a histogram of the heights of gold-medal winning high jumps in the olympic games since 1896. Which of the following statements is true? 1. in a distribution that is skewed right, the median is larger than the mean 2. fifty percent of the scores in a distribution are between the first and third quartile 3. the third quartile of a distribution is always greater than the mean 4. the median of a distribution is always greater than the mean 5. the range of a distribution is typically smaller than the interquartile range

Fifty percent of the scores in a distribution are between the first and third quartile

In order to assess the effects of exercise on reducing cholesterol, a researcher took a random sample of fifty people from a local gym who exercised regularly and another random sample of fifty people from the surrounding community who did not exercise regularly. They all reported to a clinic to have their cholesterol measured. The subjects were unaware of the study, and the technician measuring the cholesterol was not aware of whether or not subjects exercised regularly. Use Scenario 4-5. Which of the following best describes the inferences the researcher can make based on his results? 1. He can make inferences about cause and effect, but not about the populations from which the samples were taken. 2. He can make inferences about the populations from which the samples were taken, but not about the cause and effect. 3. He can make inferences about both cause and effect and the populations from which the samples were taken. 4. He cannot make inferences about either cause and effect or the populations from which the samples were taken. 5. There is not enough information to make judgments about the scope of inference.

He can make inferences about the populations from which the samples were taken, but not about cause and effect.

Jack and Jill are both enthusiastic players of a certain computer game. Over the past year, Jack's mean score when playing the game is 12,400 with a standard deviation of 1500. During the same period, Jill's mean score is 14,200, with a standard deviation of 2000. They devise a fair contest: each one will play the game once, and they will compare z-scores. Jack gets a score of 14,000, and Jill gets a score of 16,000. Who won the contest, and what were each of their z-scores? 1. Jack's z = 1.07; Jill's z = 0.90; Jack wins the contest 2. Jack's z = 1.07; Jill's z = 1.11; Jill wins the contest 3. Jack's z = 0.94; Jill's z = 0.90; Jack wins the contest 4. Jack's z = 0.94; Jill's z = 1.11; Jack wins the contest 5. Jack's z = 0.81; Jill's z = 0.99; Jill wins the contest

Jack's z = 1.07; Jill's z = 0.90; Jack wins the contest

X and Y are two categorical variables. the best way to determine if there is a relation between them is to 1. Construct parallel box plots of the X and Y values 2. Make a two-way table of the X and Y values 3. Draw dot plots of the X and Y values 4. Compare means and standard deviations of the X and Y values 5. Compare medians and interquartile ranges of the X and Y values

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

In experiment, an observed effect so large that it would rarely occur by chance is called 1. influential 2. statistically significant 3. an outlier 4. bias 5. replication

Statistically significant

For the density curve below, which of the following is true? 1. the median is 0.5 2. the density curve is skewed right 3. the median is larger than 0.5 4. the density curve is normal 5. the density curve is symmetric

The median is larger than 0.5

Below is a histogram of the heights of gold-medal winning high jumps in the olympic games since 1896. Which of the following statements is supported by this histogram? 1. The median jump is between 75 inches and 80 inches 2. the winning jump in the olympic games was 40 inches 3. the smallest jump must be below 65 inches 4. the median jump is between 80 inches and 85 inches 5. the mean jump was equal to the median jump

The median jump is between 80 and 85 inches

An assignment of probabilities must obey which of the following? 1. The probability of any event must be a number between 0 and 1, inclusive 2. The sum of all the probabilities of all outcomes in the sample space must be exactly 1 3. The probability of an event is the sum of the probabilities of outcomes in the sample space in which the event occurs 4. All of the above 5. The probability of any event must be a number between 0 and 1, inclusive & The sum of all the probabilities of all outcomes in the sample space must be exactly 1

The probability of any event must be a number between 0 and 1, inclusive & The sum of all the probabilities of all outcomes in the sample space must be exactly 1.

You measure the age, marital status and earned income of an SRS of 1463 women. The number and type of variables you have measured is 1. three; two categorical and one quantitative 2. four; one categorical, and three quantitative 3. three; one categorical and two quantitative 4. four; two categorical, and two quantitative 5. four; one categorical and two quantitative, and one individual

Three; one categorical and two quantitative

The reason that blocking (as in a randomized block design) is sometimes used in experimentation is to: 1. prevent the placebo effect 2. allow double blinding 3. eliminate the need for random assignment 4. compensate for the impact of other, unidentified variables on the response variable 5. compensate for anticipated differences in the response variable for different values of a specified "blocking" variable.

compensate for anticipated differences in the response variable for different values of a specified "blocking" variable.

Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two coups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before a mid-term exam. Use Scenario 4-6. Unfortunately, any systematic difference between the two sections on the exam might be due to the fact that the 8:30 and 9:30 classes have different instructors. This is an example of: 1. placebo effect 2. bias 3. confounding 4. observational study 5. stratification

confounding

Event A occurs with probability 0.8. The conditional probability that event B occurs, given that A occurs is 0.55. The probability that both A and B occur 1) is 0.8 2) is 0.4 3) is 0.625 4) is 0.3 5) cannot be determined from the information given

is 0.4

Are dogs better at tracking the movement of white objects or rede objects? Fifteen experienced "disk dogs" who have been trained to catch flying disks in mid-air are given the chance to catch a bright red disk or a plain white disk. Each disk is thrown 10 times for each dog, with the sequence of disks (red or white) determined randomly. The proportion of red disks caught to the proportion of white disks caught is compared for each dog. This is an example of a: 1. simple random sample 2. double-blind design 3. stratified random sample 4. matched-pairs design 5. completely randomized design

matched pairs design

The distribution of household incomes in a small town is strongly skewed to the right. The mean income is $42,000 and the standard deviation is $24,000. The Ames family's household income $60,000. The z-score for the Ames family's income is 1) -0.75 2) 0.75 3) 0.3 4) 0.86 5) none of these, because z-scores cannot be used unless the distribution is normal

none of these, because z-scores cannot be used unless the distribution is normal

Frequently, telephone poll-takers call near dinner time-between 6 pm and 7 pm-because most people are at home then. This is an effort to avoid: 1. voluntary response bias 2. calling people after they have gone to bed 3. a convenience sample 4. nonresponse 5. response bias

nonresponse

Use Scenario 3-2. The following table and scatter plot present data on wine consumption (in liters per person per year) and death rate from heart attacks (in death per 100,00 people per year) in 19 developed Western countries. The correlation between wine consumption and heart disease deaths is one of the following values. From the scatterplot, which must it be? 1. r = -0.84 2. r = -0.25 3. r is very close to 0 4. r = 0.84 5. r = 0.25

r = -0.84

Scenario 4-1. A sports writer wants to know how strongly lafayette residents support the local minor league baseball team, the Lafayette Leopards. She stands outside the stadium before a game and interviews the first 20 people who enter the stadium. Use scenario 4-1. The sample for this survey is 1. all people attending the game the day the survey was conducted 2. all leopards fans 3. al residents of lafayette 4. the 20 people who gave the sportswriter their opinion 5. the sportswriter

the 20 people who gave the sportswriter their opinion

In comparative trials in medicine, the placebo effect and subconscious bias on the part of the physicians evaluating treatment outcomes can be avoided by using: 1. the double-blind technique 2. randomized complete block design 3. response variables 4. stratified random samples 5. all of the above

the double-blind technique

A study of elementary school children, ages 6 to 11, finds a high positive correlation between shoe size x and score y on a test of reading comprehension. The observed correlation is most likely due to: 1. the effect of another variable, such as age 2. a mistake, since the correlation must be negative 3. cause and effect (larger shoe size causes higher reading comprehension). 4. "reverse" cause and effect (higher reading comprehension causes larger shoe size). 5. several outliers in the data set

the effect of another variable, such as age

A professor records the values of several variables for each student in her class. These include the variables listed below. Which of these variables are categorical? 1. Score on the final exam (out of 200 points) 2. Final grade for the course (A, B, C, D, or F) 3. Amount of time, in minutes, spent studying for the final exam 4. The total number of points earned in the class 5. The number of lectures the student missed

Final grade for the course (A, B, C, D, or F)

A poker player is dealt poor hands for several hours. He decides to bet heavily on the last hand of the evening on the grounds that after many bad hands he is due for a winner. 1. He's wrong, because successive deals are independent of each other 2. He's right, because the winnings have to average out 3. He's wrong, because he's clearly on a "cold streak" 4. He's right, because successive deals are independent of each other 5. Weather he's right or wrong depends on how many bad hands he's been dealt so far

He's wrong, because successive deals are independent of each other

The height (in feet) and volume (in cubic feet) of usable lumber of 32 cherry trees are measured by a researcher. The goal is to determine if volume of usable lumber can be estimated from the highest of a tree Using scenario 3-1. Which of the following statements are supported by the scatterplot? I. There is a positive association between height and volume. II. There is an outlier in the plot. III. As the height of a cherry tree increases, the volume of useable lumber it yields increases. 1. I only 2. II only 3. I and II 4. III only 5. I, II, and III

I, II, and III

Which of following statements are true about the least-squares regression line? I. The slope is the predicted change in the response variable associated with a unit increase in the explanatory variable. II. The line always passes through the point (x bar, y bar), the means of the explanatory and response variables, respectively. III. It is the line that minimizes the sum of the squared residuals. 1. I only 2. I and III only 3. II only 4. I, II and III are all true 5. III only

I, II, and III are all true

I toss a penny and observe whether it lands heads up or tails up. Suppose the penny is fair, i.e., the probability of heads is 1/2 and the probability of tails is 1/2. This means 1. Every occurrence of head must be balanced by a tail in one of the next two or three tosses. 2. If i flip the coin many, many times, the proportion of heads will be approximately 1/2, and this proportion will tend to get closer and closer to 1/2 as the number of tosses increases 3. Regardless of the number of flips, half will be heads and half tails 4. If I flip the coin twen times, it would be almost impossible to obtain 7 heads and 3 tails. 5. All the above

If i flip the coin many, many times, the proportion of heads will be approximately 1/2, and this proportion will tend to get closer and closer to 1/2 as the number of tosses increases