42.When conducting a hypothesis test for a given sample size, if the probability of a Type I error decreases, then the _____________. A.Probability of Type II error decreases B.Probability of incorrectly rejecting the null increases C.Probability of incorrectly accepting the null increases D.Probability of incorrectly accepting the null decreases 43.Which of the following are one-tailed... Solved Statistics Bookmark

32.A fast-food franchise is considering building a restaurant at a busy intersection. A financial advisor determines that the site is acceptable only if, on average, more than 300 automobiles pass the location per hour. If the advisor tests the hypotheses versus , µ stands for ____________. A.The average number of automobiles... Solved Statistics Bookmark

22.A professional sports organization is going to implement a test for steroids. The test gives a positive reaction in 94% of the people who have taken the steroid. However, it erroneously gives a positive reaction in 4% of the people who have not taken the steroid. What is the probability... Solved Statistics Bookmark

Multiple Choice Questions 12.The null hypothesis in a hypothesis test refers to _____________. A.The desired outcome B.The default state of nature C.The altered state of nature D.The desired state of nature 13.In general, the null and alternative hypotheses are __________. A.Additive B.Correlated C.Multiplicative D.Mutually exclusive 14.The alternative hypothesis typically ___________. A.Corresponds to the presumed default state of nature B.Contests the status quo for... Solved Statistics Bookmark

109.A doctor thinks he has found a miraculous cure for rheumatoid arthritis. He thinks it will cure more than 50% of all cases within a year of first taking the drug. To test his drug, he runs a clinical trial on 400 patients with rheumatoid arthritis. He finds that 208... Solved Statistics Bookmark

107.According to a 2009 Lawyers.com survey, only 35% of adult Americans had a will (The Wall Street Journal, December 12, 2011). Suppose a recent survey of 250 adult Americans found 100 adults with wills.a. Specify the competing hypotheses to determine whether the proportion of adult Americans that have a will... Solved Statistics Bookmark

105.A hairdresser believes that she is more profitable on Tuesdays, her lucky day of the week. She knows that, on average, she has a daily revenue of $250. She randomly samples the revenue from eight Tuesdays and finds she takes in $260, $245, $270, $260, $295, $235, $270, and $265.... Solved Statistics Bookmark

103.A company that manufactures helmets wants to test their helmets to make sure they pass SNELL certification. One of the tests the helmets are required to undergo is a test that simulates real-world impacts. During the test, crash dummies must, on average, experience a force of nearly 300 g in... Solved Statistics Bookmark

101.Students who graduated from college in 2010 with student loans owed an average of $25,250 (The New York Times, November 2, 2011). An economist wants to determine if the average debt has increased since 2010. She takes a sample of 40 recent graduates and finds that their average debt was... Solved Statistics Bookmark

99.An engineer wants to know if the average amount of energy used in his factory per day has changed since 2005. The factory used an average of 2000 megawatt hours (mwh) per day prior to 2005. Since 2005, the engineer surveyed 400 days and found the average energy use was... Solved Statistics Bookmark

97.A philanthropic organization helped a town in Africa dig several wells to gain access to clean water. Before the wells were in place, an average of 120 infants contracted typhoid each month. After the wells were installed, the philanthropic organization surveyed for nine months and found an average of 90... Solved Statistics Bookmark

95.An engineer is designing an experiment to test if airplane engines are faulty and unsafe to fly. The engineer expects 0.0001% of engines to be unsafe. The null hypothesis is that the probability of an unsafe engine is less than or equal to 0.0001% and the alternative hypothesis is that... Solved Statistics Bookmark

Essay Questions 93.Construct a null and alternative hypothesis for the following claims.a. "The school's mean GPA differs from 2.50 GPA."b. "The school's mean GPA is less than 2.50 GPA." 94.Massachusetts Institute of Technology grants pirate certificates to those students who successfully complete courses in archery, fencing, sailing, and pistol shooting ("MIT Awards... Solved Statistics Bookmark

82.Exhibit 9-5. A university interested in tracking their honors program believes that the proportion of graduates with a GPA of 3.00 or below is less than 0.20. In a sample of 200 graduates, 30 students have a GPA of 3.00 or below.Refer to Exhibit 9-5. In testing the university's belief,... Solved Statistics Bookmark

True / False Questions1.The null hypothesis typically corresponds to a presumed default state of nature. 2.The alternative hypothesis typically agrees with the status quo. 3.On the basis of sample information, we either "accept the null hypothesis" or "reject the null hypothesis." 4.As a general guideline, we use the alternative hypothesis as a vehicle... Solved Statistics Bookmark

75.When the required sample size calculated by using a formula is not a whole number, what is the best choice for the required sample size? A.Round the result of the calculation in a standard way. B.Round the result of the calculation up to the nearest whole number. C.Round the result of the... Solved Statistics Bookmark

65.Exhibit 8.4. According to a report in USA Today (February 1, 2012), more and more parents are helping their young adult children get homes. Suppose 8 persons in a random sample of 40 young adults who recently purchased a home in Kentucky got help from their parents. You have been... Solved Statistics Bookmark

55.Exhibit 8-2. The mortgage foreclosure crisis that preceded the Great Recession impacted the U.S. economy in many ways, but it also impacted the foreclosure process itself as community activists better learned how to delay foreclosure, and lenders became more wary of filing faulty documentation. Suppose the duration of the eight... Solved Statistics Bookmark

45.What is for a 95% confidence interval of the population mean based on a sample of 15 observations? A.1.761 B.1.960 C.2.131 D.2.145 46.What is for a 99% confidence interval of the population mean based on a sample of 25 observations? A.2.492 B.2.576 C.2.787 D.2.797 47.Confidence intervals of the population mean may be created for the cases when the... Solved Statistics Bookmark

35.The daily revenue from the sale of fried dough at a local street vendor in Boston is known to be normally distributed with a known standard deviation of $120. The revenue on each of the last 25 days is noted, and the average is computed as $550. A 95% confidence... Solved Statistics Bookmark

25.What is for a 95% confidence interval of the population mean? A.0.48 B.0.49 C.1.645 D.1.96 26.What is for a 90% confidence interval of the population mean? A.0.48 B.0.49 C.1.645 D.1.96 27.We draw a random sample of size 25 from the normal population with the variance 2.4. If the sample mean is 12.5, what is a 99% confidence interval... Solved Statistics Bookmark

Multiple Choice Questions 15.Which of the following is a point estimator? A. B.p C. D. 16.Which of the following is a point estimate? A. B.P C.μ D. 17.How is the unbiasness of estimators defined? A.An estimator is unbiased if its expected value equals the estimated population parameter. B.An unbiased estimator approaches the estimated population parameter as the sample size grows... Solved Statistics Bookmark

107.A large earthquake hit a city in South America. A survey of 2,000 houses found that 600 of them had collapsed. Construct a 95% confidence interval for the proportion of collapsed houses. 108.A student interviewing at a major company wants to know his chances of getting a job offer. He... Solved Statistics Bookmark

105.A large city recently surveyed 1,354 street lights, finding that 4.2% of them had burned out. Construct a 99% confidence interval for the proportion of the city's street lights that are burned out. 106.A recent survey of 1,014 American adults found that 46% view environmental conditions as either "excellent" or... Solved Statistics Bookmark

103.A large university is interested in the outcome of a course standardization process. They have taken a random sample of 100 student grades, across all instructors. The grades represent the proportion of problems answered correctly on a midterm exam. The sample proportion correct was calculated as 0.78. a. Construct a... Solved Statistics Bookmark

101.An environmentalist is measuring the number of spotted leopard lizards in central California per acre. The environmentalist surveys six acres and finds signs of 24, 26, 30, 27, 28, and 27 lizards per acre. Construct a 95% confidence interval for the average number of leopard lizards per acre. 102.A company... Solved Statistics Bookmark

99.A string quartet in Maui wants to better understand their income stream, which primarily comes from playing at weddings. The cellist records the number of weddings they play in six successive months. Construct a 90% confidence interval from her results: 3, 5, 7, 4, 4, and 5. 100.A medical engineering... Solved Statistics Bookmark

97.A job candidate with an offer from a prominent investment bank wanted to estimate how many hours she would have to work per week during her first year at the bank. She took a sample of six first-year analysts, asking how many hours they worked in the last week. Construct... Solved Statistics Bookmark

95.A sample of the weights of 35 babies is taken from the local hospital maternity ward. The point estimate for the mean weight of the babies is 110.2 ounces with a sample standard deviation of 23.4 ounces. Construct a 90% confidence interval for the population mean baby weight at this... Solved Statistics Bookmark

93.A sample of holiday shoppers is taken randomly from a local mall. Forty-nine shoppers were selected and asked what their average spending on gifts would be during the entire holiday season. The point estimate of the population mean was calculated as $550 and the sample standard deviation was calculated as... Solved Statistics Bookmark

91.Each portion of the SAT exam is designed to be normally distributed such that it has a population standard deviation of 100 and a mean of 500. However, the mean has changed over the years as less selective schools began requiring the SAT, and because students later began to prepare... Solved Statistics Bookmark

Essay Questions 89.The snowfall (in inches) during the month of January in a particular geographic region is normally distributed with a standard deviation of 16.75. In the last 12 years, the sample average of snowfall is computed as 122.50.a. Construct a 90% confidence interval of the average snowfall in this region.b.... Solved Statistics Bookmark

True / False Questions 1.A point estimate is a function of the random sample used to make inferences about the value of an unknown population parameter. A point estimator reflects the actual value of the point estimate derived from a given sample. 2.An estimator is unbiased if its expected value equals the... Solved Statistics Bookmark

76.According to the 2011 Gallup daily tracking polls (www.gallup.com, February 3, 2012), Mississippi is the most conservative U.S. state, with 53.4 percent of its residents identifying themselves as conservative.Refer to Exhibit 7-10. What is the probability that fewer than 45 respondents of a random sample of 100 Mississippi residents do... Solved Statistics Bookmark

66.The labor force participation rate is the number of people in the labor force divided by the number of people in the country that are of working age and not institutionalized. The BLS reported in February of 2012 that the labor force participation rate in the United States was 63.7%... Solved Statistics Bookmark

56.Using the central limit theorem, applied to the sampling distribution of the sample proportion, what conditions must be met? A. B. C. D. 57.A random sample of size 100 is taken from a population described by the proportion .Refer to Exhibit 7-6. What is the expected value and the standard deviation for the sampling... Solved Statistics Bookmark

46.Professor Elderman has given the same multiple choice final exam in his Principles of Microeconomics class for many years. After examining his records from the past 10 years, he finds that the scores have a mean of 76 and a standard deviation of 12.Refer to Exhibit 7-4. What is the... Solved Statistics Bookmark

36.Over the entire six years that students attend an Ohio elementary school, they are absent, on average, 28 days due to influenza. Assume that the standard deviation over this time period is days. Upon graduation from elementary school, a random sample of 36 students is taken and asked how many... Solved Statistics Bookmark

26.Statistics are used to estimate population parameters, particularly when it is impossible or too expensive to poll an entire population. A particular value of a statistic is referred to as a(n) _______. A.Mean B.Stratum C.Estimate D.Finite correction factor 27.Which of the following is considered an estimator? A. B.µ C.σ D.σ2 28.Which of the following is considered an estimate?... Solved Statistics Bookmark

Multiple Choice Questions 16.Which of the following is an example of a sample statistic? A. B.µ C.σ D.σ2 17.Which of the following is not a population parameter? A. B.µ C.σ D.σ2 18.A census is an example of __________. A.Sample data B.Sample statistic C.Population data D.Population parameter 19.Bias can occur in sampling. Bias refers to _____________________. A.The division of the population into overlapping groups B.The... Solved Statistics Bookmark

108.In a recent investigation, the National Highway Traffic Safety Administration (NHTSA) found that the Chevrolet Volt and other electric vehicles do not pose a greater risk of fire than gasoline-powered vehicles (The Boston Globe, January 25, 2012). Specifically, it was determined that "no discernible defect trend exists." Suppose a consumer... Solved Statistics Bookmark

106.In a small town, there are 3,000 registered voters. An editor of a local newspaper would like to predict the outcome of the next election; in particular he is interested in the likelihood that Eli Brady will be elected. The editor believes that Eli, a local hero, will garner 54%... Solved Statistics Bookmark

104.The Office of Career Services at a major university knows that 74% of its graduates find full-time positions in the field of their choosing within six months of graduation. Suppose the Office of Career Services surveys 25 alumni six months after graduation. a. What is the probability that at least... Solved Statistics Bookmark

102.A tutoring company claims that 75% of the high school students who hire one of their tutor's will improve their grades. a. In a sample of 100 high school students, what is the probability that 80% or more improved their grades? b. In a sample of 200 high school students,... Solved Statistics Bookmark

100.In a large metropolitan area, the top providers for television and Internet services are a phone company, a satellite company, and a cable company. The satellite company serves 43% of the homes in the area. What is the probability that in a survey of 1,000 homes, more than 447 of... Solved Statistics Bookmark

98.A gym knows that each member, on average, spends 70 minutes at the gym per week, with a standard deviation of 20 minutes. Assume the amount of time each customer spends at the gym is normally distributed. a. What is the probability that a randomly selected customer spends less than... Solved Statistics Bookmark

96.A ski resort gets an average of 2,000 customers per weekday with a standard deviation of 800 customers. Assume the underlying distribution is normal. What is the probability a ski resort averages between 1,500 customers and 3,000 customers per weekday over the course of four weekdays? 97.A mining company made... Solved Statistics Bookmark

94.Suppose residents in a well-to-do neighborhood pay an average overall tax rate of 25% with a standard deviation of 8%. Assume tax rates are normally distributed. What is the probability that the mean tax rate of 16 randomly selected residents is between 20% and 30%. 95.Suppose the average casino patron... Solved Statistics Bookmark

92.It is known that college students at a local community college study 12 hours per week with a standard deviation of 5 hours. What is the expected value and variance for a sample of nine students? 93.A fast food restaurant uses an average of 110 grams of meat per burger... Solved Statistics Bookmark

Essay Questions 90.The California Department of Education wants to gauge the difficulty of a new exam by having a sample of students at a particular school take the exam. The quality of the students at the chosen school varies widely and the school administrators are allowed to choose who gets to... Solved Statistics Bookmark