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Records from a random sample of dairy farms yielded the information below on the number of male and female calves born at various times of the day. What is the probability that a randomly selected calf was born in the night or was a female?

(a)

The five-number summary for a data set is given by min = 5, Q1 = 18, M = 20, Q3 = 40, max = 75. If you wanted to construct a modified boxplot for the data set (that is, one that would show outliers, if any existed), what would be the maximum possible length of the right-side "whisker"?

(a) 33

A large company is interested in improving the efficiency of its customer service and decides to examine the length of the business phone calls made to clients by its sales staff. A cumulative relative frequency graph is shown below from data collected over the past year. According to the graph, the shortest 80% of calls will take how long to complete?

(a) Less than 10 minutes.

Here is a dotplot of the adult literacy rates in 177 countries in 2008, according to the United Nations. For example,the lowest literacy rate was 23.6%, in the African country of Burkina Faso. Use the dotplot below to answer Questions 25 to 27. Based on the shape of this distribution, what numerical measures would best describe it?

(a) The five-number summary

For a biology project, you measure the weight in grams (g) and the tail length in millimeters (mm) of a group of mice. The equation of the least-squares line for predicting tail length from weight is predicted tail length = 20 + 3 × weight Which of the following is not correct?

(a) The slope is 3, which indicates that a mouse's weight should increase by about 3 grams for each additional millimeter of tail length.

Boxplots of two data sets are shown. Based on the boxplots, which statement below is true?

(a) The spread of both plots is about the same.

You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be shown one of the three versions and then asked about her attitude toward the product. You think there may be large differences between women who are employed and those who are not. Because of these differences, you should use

(a) a block design, but not a matched pairs design.

A grocery chain runs a prize game by giving each customer a ticket that may win a prize when the box is scratched off. Printed on the ticket is a dollar value ($500, $100, $10) or the statement, "This ticket is not a winner."Monetary prizes can be redeemed for groceries at the store. Here are the distribution of the prize values and the associated probabilities for each prize: Which of the following are the mean and standard deviation,respectively, of the winnings?

(b) $15.00, $53.85

A linear regression was performed using the five following data points: A(2, 22), B(10, 4), C(6, 14), D(14, 2), E(18, −4). The residual for which of the five points has the largest absolute value?

(b) B

A 10-question multiple-choice exam offers 5 choices for each question. Jason just guesses the answers, so he has probability 1/5 of getting any one answer correct. You want to perform a simulation to determine the number of correct answers that Jason gets. One correct way to use a table of random digits to do this is the following:

(b) One digit from the random digit table simulates one answer, with 0 or 1 = right and all other digits = wrong. Ten digits from the table simulate 10 answers.

Here is a dotplot of the adult literacy rates in 177 countries in 2008, according to the United Nations. For example,the lowest literacy rate was 23.6%, in the African country of Burkina Faso. Use the dotplot below to answer Questions 25 to 27. The overall shape of this distribution is

(b) clearly skewed to the left.

A large set of test scores has mean 60 and standard deviation 18. If each score is doubled, and then 5 is subtracted from the result, the mean and standard deviation of the new scores are

(b) mean 115; std. dev. 36

The frequency table below summarizes the times in the last month that patients at the emergency room of a small-city hospital waited to receive medical attention. Which of the following represents possible values for the median and mean waiting times for the emergency room last month?

(b) median = 28 minutes and mean = 30 minutes

Suppose we roll a fair die four times. The probability that a 6 occurs on exactly one of the rolls is

(c)

When people order books from a popular online source, they are shipped in standard-sized boxes. Suppose that the mean weight of the boxes is 1.5 pounds with a standard deviation of 0.3 pounds, the mean weight of the packing material is 0.5 pounds with a standard deviation of 0.1 pounds, and the mean weight of the books shipped is 12 pounds with a standard deviation of 3 pounds. Assuming that the weights are independent, what is the standard deviation of the total weight of the boxes that are shipped from this source?

(c) 3.02

The number of unbroken charcoal briquets in a twenty-pound bag filled at the factory follows a Normal distribution with a mean of 450 briquets and a standard deviation of 20 briquets. The company expects that a certain number of the bags will be under filled, so the company will replace for free the 5% of bags that have too few briquets. What is the minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free?

(c) 418

For a certain experiment, the available experimental units are eight rats, of which four are female (F1, F2, F3, F4) and four are male (M1, M2, M3, M4). There are to be four treatment groups, A, B, C, and D. If a randomized block design is used, with the experimental units blocked by gender, which of the following assignments of treatments is impossible?

(c) A → (F1, M2), B → (F3, F2), C → (F4, M1), D → (M3, M4)

Social scientists are interested in the association between high school graduation rate (HSGR) and the percent of U.S. families living in poverty (POV). Data were collected from all 50 states and the District of Columbia, and a regression analysis was conducted. The resulting least-squares regression line is given by: with r2 = 0.802. Based on the information, which of the following is the best interpretation for the slope of the least-squares regression line?

(c) For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.620.

The correlation between the age and height of children under the age of 12 is found to be r = 0.60. Suppose we use the age x of a child to predict the height y of the child. What can we conclude?

(c) The fraction of the variation in heights explained by the least-squares regression line of y on x is 0.36.

Here is a dotplot of the adult literacy rates in 177 countries in 2008, according to the United Nations. For example,the lowest literacy rate was 23.6%, in the African country of Burkina Faso. Use the dotplot below to answer Questions 25 to 27. The mean of this distribution (don't try to find it) will be

(c) less than the median.

The figure below shows a Normal density curve. Which of the following gives the best estimates for the mean and standard deviation of this Normal distribution?

(c) μ = 225, σ = 50

Suppose that you have torn a tendon and are facing surgery to repair it. The orthopedic surgeon explains the risks to you. Infection occurs in 3% of such operations, the repair fails in 14%, and both infection and failure occur together 1% of the time. What is the probability that the operation is successful for someone who has an operation that is free from infection?

(d) 0.8660

The probability distribution for the number of heads in four tosses of a coin is given by: The probability of getting at least one tail in four tosses of a coin is

(d) 0.9375.

Before he goes to bed each night, Mr. Kleen pours dishwasher powder into his dishwasher and turns it on. Each morning, Mrs. Kleen weighs the box of dishwasher powder. From an examination of the data, she concludes that Mr. Kleen dispenses a rather consistent amount of powder each night. Which of the following statements is true? I. There is a high positive correlation between the number of days that have passed since the box of dishwasher powder was opened and the amount of powder left in the box. II. A scatter plot with days since purchase as the explanatory variable and amount of dishwasher powder used as the response variable would display a strong positive association. III. The correlation between the amount of powder left in the box and the amount of powder used should be −1.

(d) II and III only

You look at real estate ads for houses in Sarasota, Florida. Many houses range from $200,000 to $400,000 in price. The few houses on the water, however, have prices up to $15 million. Which of the following statements best describes the distribution of home prices in Sarasota?

(d) The distribution is most likely skewed to the right, and the mean is greater than the median.

You are planning an experiment to determine the effect of the brand of gasoline and the weight of a car on gas mileage measured in miles per gallon. You will use a single test car, adding weights so that its total weight is 3000,3500, or 4000 pounds. The car will drive on a test track at each weight using each of Amoco, Marathon, and Speedway gasoline. Which is the best way to organize the study?

(d) There are nine combinations of weight and gasoline. Run the car several times using each of these combinations. Make all these runs in random order.

An agronomist wants to test three different types of fertilizer (A, B, and C) on the yield of a new variety of wheat. The yield will be measured in bushels per acre. Six one-acre plots of land were randomly assigned to each of the three fertilizers. The treatment, experimental unit, and response variable are, respectively,

(d) a specific fertilizer, a plot of land, bushels per acre.

The General Social Survey (GSS), conducted by the National Opinion Research Center at the University of Chicago, is a major source of data on social attitudes in the United States. Once each year, 1500 adults areinterviewed in their homes all across the country. The subjects are asked their opinions about sex and marriage,attitudes toward women, welfare, foreign policy, and many other issues. The GSS begins by selecting a sample ofcounties from the 3000 counties in the country. The counties are divided into urban, rural, and suburban; a separatesample is chosen at random from each group. This is a

(d) stratified random sample

A child is 40 inches tall, which places her at the 90th percentile of all children of similar age. The heights for children of this age form an approximately Normal distribution with a mean of 38 inches. Based on this information,what is the standard deviation of the heights of all children of this age?

(e) 1.56 inches

You want to take an SRS of 50 of the 816 students who live in a dormitory on a college campus. You label the students 001 to 816 in alphabetical order. In the table of random digits, you read the entries 95592 94007 69769 33547 72450 16632 81194 14873 The first three students in your sample have labels

(e) 400, 769, 335.

Here are the IQ scores of 10 randomly chosen fifth-grade students:145 139 126 122 125 130 96 110 118 118 Which of the following statements about this data set is not true?

(e) If the value 96 were removed from the data set, the IQR of the remaining 9 IQ scores would be lower than the IQR of all 10 IQ scores.

Which one of the following would be a correct interpretation if you have a z-score of +2.0 on an exam?

(e) It means that your grade is two standard deviations above the mean for this exam.

The owner of a chain of supermarkets notices that there is a positive correlation between the sales of beer and the sales of ice cream over the course of the previous year. During seasons when sales of beer were above average, sales of ice cream also tended to be above average. Likewise, during seasons when sales of beer were below average,sales of ice cream also tended to be below average. Which of the following would be a valid conclusion from these facts?

(e) The positive correlation is most likely a result of the lurking variable temperature; that is, as temperatures increase, so do both beer sales and ice cream sales.

In a certain large population of adults, the distribution of IQ scores is strongly left-skewed with a mean of 122 and a standard deviation of 5. Suppose 200 adults are randomly selected from this population for a market researchstudy. The distribution of the sample mean of IQ scores is

(e) approximately Normal with mean 122 and standard deviation 0.35.