1) The chancellor of a major university was concerned about alcohol abuse on her campus and wanted to find out the proportion of students at her university who visited campus bars on the weekend before the final exam week. Her assistant took a random sample of 250 students. The portion of students in the sample who visited campus bars on the weekend before the final exam week is an example of
A) a statistic. B) a parameter. C) a population.D) a sample.
2) Which of the following statistics is not a measure of central tendency?
A) arithmetic mean B) mode C) median D)
3) Data on the change in the cost of tuition, a shared dormitory room, and the most popular meal plan from the 2007-2008 academic year to the 2008-2009 academic year for a sample of 100 public universities are collected. Below is the boxplot for the change in cost in dollars. The distribution of the change in cost is
A) none of the above B) symmetrical C) left-skewed D) right-skewed
4) Which of the following is sensitive to extreme values?
A) the interquartile range B) the arithmetic mean C) the 1st quartile D) the median
5) If two equally likely events A and B are mutually exclusive, what is the probability that event A occurs?
A) 0.50 B) 1.00 C) 0 D) Cannot be determined from the information given.
6) In its standardized form, the normal distribution
A) has an area equal to 0.5. B) has a mean of 0 and a standard deviation of 1. C) cannot be used to approximate discrete probability distributions. D) has a mean of 1 and a variance of 0
7) The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and standard deviation of 0.8 pound. If a sample of 16 fish is taken, what would the standard error of the mean weight equal?
8) The head librarian at the Library of Congress has asked her assistant for an interval estimate of the mean number of books checked out each day. The assistant provides the following interval estimate: from 740 to 920 books per day. If the head librarian knows that the population standard deviation is 150 books checked out per day, and she asked her assistant for a 95% confidence interval, approximately how large a sample did her assistant use to determine the interval estimate?
9) A confidence interval was used to estimate the proportion of statistics students that are females. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Based on the interval above, is the population proportion of females equal to 0.60?
The quality control engineer for a furniture manufacturer is interested in the mean amount of force necessary to produce cracks in stressed oak furniture. She performs a two-tail test of the null hypothesis that the mean for the stressed oak furniture is 650. The calculated value of the Z test statistic is a positive number that leads to a p-value of 0.080 for the test.
10) Referring to Table 9-6, suppose the engineer had decided that the alternative hypothesis to test was that the mean was greater than 650. What would be the p-value of this one-tail test?
11) How many tissues should the Kimberly Clark Corporation package of Kleenex contain? Researchers determined that 60 tissues is the mean number of tissues used during a cold. Suppose a random sample of 100 Kleenex users yielded the following data on the number of tissues used during a cold: = 52, S = 22. Suppose the test statistic does fall in the rejection region at α = 0.05. Which of the following decisions is correct?
The use of preservatives by food processors has become a controversial issue. Suppose 2 preservatives are extensively tested and determined safe for use in meats. A processor wants to compare the preservatives for their effects on retarding spoilage. Suppose 15 cuts of fresh meat are treated with preservative I and 15 are treated with preservative II, and the number of hours until spoilage begins is recorded for each of the 30 cuts of meat. The results are summarized in the table below. Preservative I Preservative II
12) Referring to Table 10-3
A) There is evidence that the population variances between preservatives I and II are the same. B) There is evidence of a difference in the population variances between preservatives I and II. C) There is no evidence of a difference in the population variances between preservatives I and II. D) There is no evidence that the population variances between preservatives I and II are the same.
The dean of a college is interested in the proportion of graduates from his college who have a job offer on graduation day. He is particularly interested in seeing if there is a difference in this proportion for accounting and economics majors. In a random sample of 100 of each type of major at graduation, he found that 65 accounting majors and 52 economics majors had job offers. If the accounting majors are designated as "Group 1" and the economics majors are designated as "Group 2," perform the appropriate hypothesis test using a level of significance of 0.05.
13) Referring to Table 10-12, the hypotheses the dean should use are:
A) H0 : π1 - π2 ≥ 0 versus H1: π1 - π2 < 0 B) H0 : π1 - π2 ≠ 0 versus H1: π1 - π2 = 0 C) H0 : π1 - π2 ≤ 0 versus H1: π1 - π2 > 0 D) H0 : π1 - π2 = 0 versus H1: π1 - π2 ≠ 0
A campus researcher wanted to investigate the factors that affect visitor travel time in a complex, multilevel building on campus. Specifically, he wanted to determine whether different building signs (building maps versus wall signage) affect the total amount of time visitors require to reach their destination and whether that time depends on whether the starting location is inside or outside the building. Three subjects were assigned to each of the combinations of signs and starting locations, and travel time in seconds from beginning to destination was recorded. An Excel output of the appropriate analysis is given below:
14) Referring to Table 11-4, the F test statistic for testing the main effect of types of signs is
A) 3.1742 B) 0.0109 C) 5.3176 D) 2.7844
A computer software developer would like to use the number of downloads (in thousands) for the trial version of his new shareware to predict the amount of revenue (in thousands of dollars) he can make on the full version of the new shareware. Following is the output from a simple linear regression along with the residual plot and normal probability plot obtained from a data set of 30 different sharewares that he has developed:
15) Referring to Table 13-11, which of the following is the correct null hypothesis for testing whether there is a linear relationship between revenue and the number of downloads?
A) H0 : β1 ≠ 0 B) H0 : β1 = 0 C) H0 : b1 = 0 D) H0 : b1 ≠ 0
16) According to the empirical rule, if the data form a "bell-shaped" normal distribution, ________ percent of the observations will be contained within 3 standard deviations around the arithmetic mean.
A) 68.26 B) 95.0 C) 75.00D) 99.7
17) If a particular batch of data is approximately normally distributed, we would find that approximately
A) 4 of every 5 observations would fall between ± 1.28 standard deviations around the mean. B) 2 of every 3 observations would fall between ± 1 standard deviation around the mean. C) 19 of every 20 observations would fall between ± 2 standard deviations around the mean. D) All of the above
18) A population frame for a survey contains a listing of 6,179 names. Using a table of random numbers, which of the following code numbers will appear on your list?
A) 0694 B) 61790 C) 6946 D) 06
19) Suppose a 95% confidence interval for μ turns out to be (1,000, 2,100). Give a definition of what it means to be "95% confident" in an inference.
A) 95% of the observations in the entire population fall in the given interval. B) In repeated sampling, the population parameter would fall in the given interval 95% of the time. C) In repeated sampling, 95% of the intervals constructed would contain the population mean. D) 95% of the observations in the sample fall in the given interval.
A drug company is considering marketing a new local anesthetic. The effective time of the anesthetic the drug company is currently producing has a normal distribution with an mean of 7.4 minutes with a standard deviation of 1.2 minutes. The chemistry of the new anesthetic is such that the effective time should be normally distributed with the same standard deviation, but the mean effective time may be lower. If it is lower, the drug company will market the new anesthetic; otherwise, they will continue to produce the older one. A sample of size 36 results in a sample mean of 7.1. A hypothesis test will be done to help make the decision.
20) Referring to Table 9-4, the appropriate hypotheses are:
A) H0 : μ = 7.4 versus H1 : μ ≠ 7.4 B) H0 : μ ≤ 7.4 versus H1 : μ > 7.4 C) H0 : μ > 7.4 versus H1 : μ ≤ 7.4 D) H0 : μ ≥ 7.4 versus H1 : μ < 7.4
A real estate company is interested in testing whether, on average, families in Gotham have been living in their current homes for less time than families in Metropolis have. Assume that the two population variances are equal. A random sample of 100 families from Gotham and a random sample of 150 families in Metropolis yield the following data on length of residence in current homes. Gotham: G = 35 months, SG 2 = 900 Metropolis: M = 50 months, SM2 = 1050
21) Referring to Table 10-4, suppose α = 0.01. Which of the following represents the correct conclusion?
A) There is enough evidence that the mean amount of time families in Gotham have been living in their current homes is not less than families in Metropolis. B) There is not enough evidence that the mean amount of time families in Gotham have been living in their current homes is less than families in Metropolis. C) There is not enough evidence that the mean amount of time families in Gotham have been living in their current homes is not less than families in Metropolis. D) There is enough evidence that the mean amount of time families in Gotham have been living in their current homes is less than families in Metropolis.
22) Which of the following is most likely a parameter as opposed to a statistic?
A) The average score of the first five students completing an assignment. B) The average height of people randomly selected from a database. C) The proportion of females registered to vote in a county. D) The proportion of trucks stopped yesterday that were cited for bad brakes.
23) You have collected information on the consumption by the 15 largest coffee-consuming nations. Which of the following is the best for presenting the shares of the consumption?
A) A contingency table. B) A pie chart. C) A side-by-side bar chart. D) A Pareto chart.
24) In a right-skewed distribution
A) the median is larger than the arithmetic mean. B) the median equals the arithmetic mean. C) the median is less than the arithmetic mean. D) None of the above
25) When using the general multiplication rule, P(A and B) is equal to
A) P(A|B)P(B). B) P(A)/P(B). C) P(A)P(B). D) P(B)/P(A)
26) For some value of Z, the probability that a standard normal variable is below Z is 0.2090. The value of Z is: 26) ______ A) 0.31 B) - 0.31C) - 0.81 D) 1.96
27) For air travelers, one of the biggest complaints is of the waiting time between when the airplane taxis away from the terminal until the flight takes off. This waiting time is known to have a skewed-right distribution with a mean of 10 minutes and a standard deviation of 8 minutes. Suppose 100 flights have been randomly sampled. Describe the sampling distribution of the mean waiting time between when the airplane taxis away from the terminal until the flight takes off for these 100 flights.
28) In the construction of confidence intervals, if all other quantities are unchanged, an increase in the sample size will lead to a interval.
A) wider B) biased C) narrower D) less significant
29) You know that the level of significance (α) of a test is 5%, you can tell that the probability of committing a Type II error (β) is
A) 2.5%. B) unknown. C) 95%. D) 97.5%.
A realtor wants to compare the average sales-to-appraisal ratios of residential properties sold in four neighborhoods (A, B, C, and D). Four properties are randomly selected from each neighborhood and the ratios recorded for each, as shown below. A: 1.2, 1.1, 0.9, 0.4 C: 1.0, 1.5, 1.1, 1.3 B: 2.5, 2.1, 1.9, 1.6 D: 0.8, 1.3, 1.1, 0.7
30) Referring to Table 11-3, the critical value of Levene's test for homogeneity of variances at a 5% level of significance is
A) 3.29 B) 0.64 C) 3.49 D) 2.48