Question: How long does it take to become

> Generic drug sales make up about half of all prescriptions sold in the United States. The marketing manager for a pharmaceutical company wanted to acquire more information about the sales of generic prescription drugs. To do so, she randomly sampled 475

> An increasing number of North Americans regularly take vitamins or herbal remedies daily. To gauge this phenomenon, a random sample of Americans was asked to report the number of vitamin and herbal supplements they take daily. Estimate with 95% confidenc

> OfficeMax, a chain that sells a wide variety of office equipment often features sales of products whose prices are reduced because of rebates. Some rebates are so large that the effective price becomes $0. The goal is to lure customers into the store to

> Bankers and economists watch for signs that the economy is slowing. One statistic they monitor is consumer debt, particularly credit card debt. The Federal Reserve conducts surveys of consumer finances every 3 years. The last survey determined that 23.8%

> A random sample of American adults was asked whether or not they smoked cigarettes. Those who responded affirmatively were asked how many cigarettes they smoked per day. Assuming that there are 50 million American adults who smoke, estimate with 95% conf

> A company that produces universal remote controls wanted to determine the number of remote-control devices American homes contain. The company hired a statistician to survey 240 randomly selected homes and determine the number of remote controls. If ther

> A growing concern for educators in the United States is the number of teenagers who have part-time jobs while they attend high school. It is generally believed that the amount of time teenagers spend working is deducted from the amount of time devoted to

> University bookstores order books that instructors adopt for their courses. The number of copies ordered matches the projected demand. However, at the end of the semester, the bookstore has too many copies on hand and must return them to the publisher. A

> Most owners of digital cameras store their pictures on the camera. Some will eventually download these to a computer or print them using their own printers or a commercial printer. A film-processing company wanted to know how many pictures were stored on

> Part of a university professor’s job is to publish his or her research. This task often entails reading a variety of journal articles to keep up to date. To help determine faculty standards, a dean of a business school surveyed a random sample of 12 prof

> A parking control officer is conducting an analysis of the amount of time left on parking meters. A quick survey of 15 cars that have just left their metered parking spaces produced the following times (in minutes). Estimate with 95% confidence the mean

> A federal agency responsible for enforcing laws governing weights and measures routinely inspects packages to determine whether the weight of the contents is at least as great as that advertised on the package. A random sample of 18 containers whose pack

> A diet doctor claims that the average North American is more than 20 pounds overweight. To test his claim, a random sample of 20 North Americans was weighed, and the difference between their actual and ideal weights was calculated. The data are listed he

> How much money do winners go home with from the television quiz show Jeopardy? To determine an answer, a random sample of winners was drawn; the recorded amount of money each won is listed here. Estimate with 95% confidence the mean winnings for all the

> A courier service advertises that its average delivery time is less than 6 hours for local deliveries. A random sample of times for 12 deliveries to an address across town was recorded. These data are shown here. Is this sufficient evidence to support th

> a. Test the following hypotheses with = .05 given that x = 405, s = 100, and n = 1,000. b. Repeat part (a) assuming that you know that the population standard deviation is = 100. c. Explain why the conclusions produced in parts (a) and (b) are virtuall

> a. A statistics practitioner randomly sampled 1,500 observations and found x = 14 and s = 25. Test to determine whether there is enough evidence at the 5% significance level to infer that the population mean is less than 15. b. Repeat part (a) assuming t

> a. Compute the p-value in order to test the following hypotheses given that x = 52, n = 9, and σ = 5. H0: μ = 50 H1: μ > 50 b. Repeat part (a) with n = 25. c. Repeat part (a) with n = 100. d. Describe what happens to the value of the test statistic and i

> a. A statistics practitioner randomly sampled 10 observations and found x = 103 and s = 17. Is there sufficient evidence at the 10% significance level to conclude that the population mean is less than 110? b. Repeat part (a) assuming that you know that t

> a. A random sample of 11 observations was taken from a normal population. The sample mean and standard deviation are x = 74.5 and s = 9. Can we infer at the 5% significance level that the population mean is greater than 70? b. Repeat part (a) assuming th

> a. In a random sample of 500 observations drawn from a normal population, the sample mean and sample standard deviation were calculated as x = 350 and s = 100. Estimate the population mean with 99% confidence. b. Repeat part (a) assuming that you know th

> a. After sampling 1,000 members of a normal population, you find x = 15,500 and s = 9,950. Estimate the population mean with 90% confidence. b. Repeat part (a) assuming that you know that the population standard deviation is  = 9,950. c. Explain why the

> a. Estimate the population mean with 90% confidence given the following: x = 175, s = 30, and n = 5. b. Repeat part (a) assuming that you know that the population standard deviation is  = 30. c. Explain why the interval estimate produced in part (b) is

> A random sample of 8 observations was drawn from a normal population. The sample mean and sample standard deviation are x = 40 and s = 10. a. Estimate the population mean with 95% confidence. b. Repeat part (a) assuming that you know that the population

> a. To test the following hypotheses, a statistics practitioner randomly sampled 100 observations and found x = 106 and s = 35. Calculate the test statistic (and for Excel users, the p -value) of a test to determine whether there is enough evidence at the

> a. A statistics practitioner wishes to test the following hypotheses: A sample of 50 observations yielded the statistics x = 585 and s = 45. Calculate the test statistic (and for Excel users, the p-value) of a test to determine whether there is enough e

> a. A random sample of 25 observations was drawn from a normal population. The sample mean and sample standard deviation are x = 52 and s = 15. Calculate the test statistic (and for Excel users, the p-value) of a test to determine if there is enough evide

> a. Calculate the test statistic (and for Excel users, the p -value) when x = 145, s = 50, and n = 100. Use a 5% significance level. b. Repeat part (a) with x = 140. c. Repeat part (a) with x = 135. d. What happens to the t-statistic (and for Excel users

> In the 2010 census, 16.8% of American adults entered college but did not finish. Using the data from the Survey of Consumer Finances of 2013 test, determine whether that figure increased (EDCL: 3 = Some college).

> The proportion of Americans living in homes that they owned in 2010 was 65.8%. Is there sufficient evidence to infer that that figure increased by 2013? (HOUSECL: 1 = Owns)

> a. A statistics practitioner is in the process of testing to determine whether there is enough evidence to infer that the population mean is different from 180. She calculated the mean and standard deviation of a sample of 200 observations as x = 175 and

> In the 2010 census, the proportion of Black/African Americans was 12.9%. Has that percentage decreased? Conduct a test using the Survey of Consumer Finances of 2013 to answer the question (RACE: 2 = Black/African American).

> Because interest paid by banks on money left in savings accounts is so low, people are advised to keep very little in these accounts. To determine if people are following that advice, estimate the amount of money kept in savings accounts by middle-class

> How well educated are people in middle-class households? According to the U.S. Census the average American adult has completed 12.9 years of schooling. Is there enough evidence to conclude that the average middle class head of household has more educatio

> The interest rates charged by credit card companies is so high that consumers are advised to pay off their credit card debt as quickly as possible. To see if people are following this advice, estimate the credit card balance held by middle-class househol

> According to the United Census the average expenditure for food away from home was $2625. Is there enough evidence to infer that the average middle-class households spend less (FOODAWAY)?

> In the United States, there is no capital gains on houses until the last one is sold. Up to that point any gains are considered unrealized capital gains or losses on primary residence. Estimate the capital gains on the primary residence for middle class

> In 2013, the housing market started picking up. Were people getting themselves too much into debt and hoping that the price of their homes would increase? One way to judge is to determine the size of mortgages (NH_MORT). Estimate the amount owed on mortg

> There is no single definition of the middle class in the United States. For the purposes of analyzing the data from the Survey of Consumer Finances we have defined middle class on the basis of net worth. However, many economists define middle class on th

> There are a variety of ways in which households have debt. The largest is probably the mortgage on the home they live in. Others include student debt, vehicle loans, and credit card debt. a. To determine how much debt is carried by middle- class American

> A large number of American families are invested in the stock market. Many have various pension plans that use contributed funds to buy stocks. Many others have directly held shares in the stock market. a. Estimate the mean total value of stocks held dir

> a. The sample mean and standard deviation from a random sample of 10 observations from a normal population were computed as x = 23 and s = 9. Calculate the value of the test statistic (and for Excel users, the p-value) of the test required to determine w

> How much money do middle- class Americans keep in their checking account (CHECKING)? a. Estimate the mean amount held in checking accounts. b. What is the required condition? c. Is it satisfied?

> Because to be in the middle class requires a net worth of at least $67,300, we would expect the average age (AGE) of middle-class American adults to be greater than the average age of all-American adults, which is 50.4. a. Conduct a test to determine whe

> According to the Bureau of Labor Statistics, the average American family spent $2625 on food at restaurants. Is there enough evidence that wealthy households spend more than twice that figure (FOODAWAY)?

> Checking accounts are often used for household expenditures. Because they pay no interest, most households including wealthy ones keep a minimum amount in these accounts. a. Estimate the mean total value of checking accounts held by wealthy households (C

> Net worth is defined as the difference between total assets and total liabilities including debt. Does high net worth mean that these households have little or no debt? a. Answer the question by estimating the mean debt of all wealthy households (DEBT).

> Do wealthy households have late payments? Estimate the proportion of wealthy households that had at least one late payment in the previous year (LATE: 1).

> How does one get to be in this class whose minimum household net worth is about $9.5 million. Could this be achieved through high income alone? Examine this issue by estimating the mean annual income of wealthy households (INCOME).

> Is a graduate degree a pathway to a wealthy household? Estimate the proportion of wealthy households whose heads have graduate degrees (EDUC: 17 = Graduate school).

> Another sign of financial difficulties is when a household finds that overall expenses are unusually high. Estimate with 99% confidence the number of households whose expenses are unusually high (EXPENSHILO: 1 = Unusually high).

> a. The sample mean and standard deviation from a sample of 81 observations are x = 63 and s = 8. Estimate  with 95% confidence. b. Repeat part (a) with n = 64. c. Repeat part (a) with n = 36. d. Describe what happens to the confidence interval estimate

> Another sign of financial problems is when a household is late with at least one payment. Estimate with 90% confidence the number of households that had a least one late payment in the preceding 12 months (LATE: 1 = Yes).

> Government debt and personal debt are a growing concern. Estimate the number of households that have debts (HDEBT: 1 = Yes).

> How many American adults (18 and over) are working in some way? Estimate the number (LF: 1 = Working in some way).

> If there was gender equality in the head of household designation the number of households with male’s head of households would equal the number of households with females as heads of households. Conduct a test to determine that there is no gender equali

> The 2010 Census showed that the percentage of American adults who had an advanced degree (Read: graduate) was 10.5%. Is there sufficient evidence to infer that by 2013 that figure had been increased (EDUC: 17 = Graduate school)?

> The 2010 census showed that the percentage of Black Americans who did not finish high school was 15.8%. Did this figure decrease by 2013? Conduct a test to determine whether there is enough evidence to infer that the proportion of Black Americans who did

> The proportion of women who did not finish high school was 12.4% according to the census in 2010. Is there enough statistical evidence to conclude that the proportion has decreased in 2013 (HHSEX: 2 = Female; EDCL: 1 = No high school diploma)?

> The birth rate in many countries is falling. This will create problems in the future because there will be less people contributing taxes and more retired people receiving government pensions. The birth rate needed to maintain current population levels i

> Is there a contradiction between the results in Exercises 12.175 and 12.176? Explain.

> Among Liberals and Conservatives only is there enough evidence to infer that there are more Conservatives than Liberals (POLVIEWS3: 1 = Liberal, 3 = Conservative)?

> a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are x = 120 and s = 15. Estimate the population mean with 95% confidence. b. Repeat part (a) with a 90% confidence level. c. Repeat part (a) with an 80% con

> Among Democratic and Republicans only is there enough evidence to infer that there are more Democrats than Republicans (PARTYID3: 1 = Democrat, 3 = Republican)? (Caution: Tricky question)

> Is the entrepreneurial spirit of the United States alive and well? Estimate with 95% confidence the number of Americans who work for themselves (WRKSLF: 1 = Self-employed).

> How many people work for the federal, state, or local government? Estimate with 95% confidence the number of adults (18 and over) who work for the federal, state, or local government (WRKGOVT: 1 = Government).

> It has been said that America is a nation of immigrants. Estimate with 95% confidence the number of Americans 18 and over who were born outside the United States (BORN: 2 = Born outside the United States).

> According to the 2010 census, among people who were never married the percentage who did not finish high school was 14.0%. Has the proportion in 2014 increased? Perform a statistical test to answer the question (MARITAL: 5 = Never married; DEGREE: 0 = Le

> An increasing number of women are attending university. Women now outnumber men in most college programs. In the 2010 census, the proportion of women with graduate degrees was 10.2% (The census used “advanced” to represent graduate degrees.) Can we infer

> In the 2010 census, the proportion of divorced White Americans was 10.4%. Has that percentage in 2014 increased? Conduct a statistical test to answer the question (RACE: 1 = White; MARITAL: 3 = Divorced).

> Since 2010 the number of jobs available for people who have not completed high school has decreased. Has this resulted in a change in the proportion of Americans who did not complete high school? Perform a statistical test to answer the question (DEGREE:

> In 2010, the United States was just recovering from the housing debacle. The percentage of home ownership was 65.8%. Is there enough evidence to infer that the proportion of home ownership has changed since then (DWELOWN: 1 = Own)?

> Has the proportion of Americans who were never married changed since the census? Conduct a test to answer the question (MARITAL: 5 = Never married).

> a. The mean and standard deviation of a sample of 100 are x = 10 and s = 1. Estimate the population mean with 95% confidence. b. Repeat part (a) with s = 4. c. Repeat part (a) with s = 10. d. Discuss the effect on the confidence interval estimate of incr

> V C12-03 virtually all countries have universal government run health-care systems. The United States is one notable exception. This is an issue in every election, with some politicians pushing for the United States to adopt a program similar to Canada&a

> While the executives of Pepsi Cola are trying to decide what to do, the university informs them that a similar offer has gone out to the Coca-Cola Company. Furthermore, if both companies want exclusive rights, a bidding war will take place. The executive

> In the last few years, colleges and universities have signed exclusivity agreements with a variety of private companies. These agreements bind the university to sell that company’s products exclusively on the campus. Many of the agreements involve food a

> The game of roulette consists of a wheel with 38 colored and numbered slots. The numbers are 1 to 36, 0 and 00. Half of the slots numbered 1 to 36 are red and the other half are black. The two “zeros” are green. The wh

> As the U.S. population ages, the number of people needing medical care increases. Unless a cure is found in the next decade, one of the most expensive diseases requiring such care is Alzheimer’s, a form of dementia. To estimate the tota

> Use the χ2 table (Table 5) to find the following values of χ2. a. χ2 .10, 5 b. χ2 .01, 100 c. χ2 .95, 18 d. χ2 .99, 60 Data from Table 5: TABLE 8.5 Critical Values of x35, a and x3

> Use a computer to find the following probabilities. a. P(t141 > .94) b. P(t421 > 2.00) c. P(t1000 > 1.96) d. P(t82 > 1.96)

> Use a computer to find the following probabilities. a. P(t64 > 2.12) b. P(t27 > 1.90) c. P(t159 > 1.33) d. P(t550 > 1.85)

> Use a computer to find the following values of t. a. t.05, 143 b. t.01, 12 c. t.025,∞ d. t.05, 100

> Use a computer to find the following values of t. a. t.10, 15 b. t.10, 23 c. t.025, 83 d. t.05, 195

> a. A statistics practitioner drew a random sample of 400 observations and found that x = 700 and s = 100. Estimate the population mean with 90% confidence. b. Repeat part (a) with a 95% confidence level. c. Repeat part (a) with a 99% confidence level. d.

> Use the t table (Table 4) to find the following values of t. a. t.005, 33 b. t.10, 600 c. t.05, 4 d. t.01, 20

> Use the t table (Table 4) to find the following values of t. a. t.10, 15 b. t.10, 23 c. t.025, 83 d. t.05, 195

> A Jiffy Lube franchise manager is concerned about the amount of time it takes for his technicians to change the oil and filters of cars. The current mean time for the complete operation is 18 minutes. He hasn’t kept track of the number of times his emplo

> Refer to Exercise 8.85. In order to improve the time spent by trucks waiting, both countries should improve the service rate by customs agents. Suppose that the governments decided that the probability that a truck spends more than 30 minutes being check

> The manager of a supermarket tracked the amount of time needed for customers to be served by the cashier. After checking with his statistics professor, he concluded that the checkout times are exponentially distributed with a mean of 6 minutes. What prop

> Calculate the value of the test statistic, set up the rejection region, determine the p-value, interpret the result, and draw the sampling distribution. H0: μ = 15 H1: μ < 15 σ = 2, n = 25, x = 14.3, α = .10

> Because automatic banking machine (ABM) customers can perform a number of transactions, the times to complete them can be quite variable. A banking consultant has noted that the times are exponentially distributed with a mean of 125 seconds. What proport

> The manager of a gas station has observed that the times required by drivers to fill their car’s tank and pay are quite variable. In fact, the times are exponentially distributed with a mean of 7.5 minutes. What is the probability that a car can complete

> Toll booths on the New York State Thruway are often congested because of the large number of cars waiting to pay. A consultant working for the state concluded that if service times are measured from the time a car stops in line until it leaves, service t

> A bank wishing to increase its customer base advertises that it has the fastest service and that virtually all of its customers are served in less than 10 minutes. A management scientist has studied the service times and concluded that service times are

> a. The mean and standard deviation of a sample of 100 is x = 1500 and s = 300. Estimate the population mean with 95% confidence. b. Repeat part (a) with s = 200. c. Repeat part (a) with s = 100. d. Discuss the effect on the confidence interval estimate o

> Canada and the United States are each other’s largest trading partner. The two-way trade between these two countries is the largest in the world. This makes the Ambassador bridge linking Windsor Ontario and Detroit Michigan extremely busy. The Free Trade

> The time between breakdowns of aging machines is known to be exponentially distributed with a mean of 25 hours. The machine has just been repaired. Determine the probability that the next breakdown occurs more than 50 hours from now.

> The production of a complex chemical needed for anticancer drugs is exponentially distributed with λ = 6 kilograms per hour. What is the probability that the production process requires more than 15 minutes to produce the next kilogram of drugs?

> X is an exponential random variable with λ = .3. Find the following probabilities. a. P(X > 2) b. P(X < 4) c. P(1 < X < 2) d. P(X = 3)