[SOLVED] Redo Example 11.2 with a. n =

> 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)

> Let X be an exponential random variable with λ = .5. Find the following probabilities. a. P(X > 1) b. P(X > .4) c. P(X < .5) d. P(X < 2)

> X is an exponential random variable with λ = .25. Sketch the graph of the distribution of X by plotting and connecting the points representing f(x) for x = 0, 2, 4, 6, 8, 10, 15, 20.

> 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 = 50 H1: μ > 50 σ = 5, n = 9, x = 51, α = .03

> The number of potential sites for the first-stage test in Exercise 11.78 is quite large and the readings can be expensive. Accordingly, the test is conducted with a sample of 25 observations. Because the second stage cost is high, the significance level

> The feasibility of constructing a profitable electricity producing windmill depends on the mean velocity of the wind. For a certain type of windmill, the mean would have to exceed 20 miles per hour to warrant its construction. The determination of a site

> A school-board administrator believes that the average number of days absent per year among students is less than 10 days. From past experience, he knows that the population standard deviation is 3 days. In testing to determine whether his belief is true

> a. A random sample of 25 was drawn from a population. The sample mean and standard deviation are x = 510 and s = 125. Estimate with 95% confidence. b. Repeat part (a) with n = 50. c. Repeat part (a) with n = 100. d. Describe what happens to the confide

> Refer to Exercise 11.54. A financial analyst has determined that a 2-minute reduction in the average break would increase productivity. As a result, the company would hate to lose this opportunity. Calculate the probability of erroneously concluding that

> The fast-food franchiser in Exercise 11.51 was unable to provide enough evidence that the site is acceptable. She is concerned that she may be missing an opportunity to locate the restaurant in a profitable location. She feels that if the actual mean is

> The test of hypothesis in the SSA example concluded that there was not enough evidence to infer that the plan would be profitable. The company would hate to not institute the plan if the actual reduction was as little as 3 days (i.e., μ = 21). Calculate

> In Exercise 11.47, we tested to determine whether the installation of safety equipment was effective in reducing person-hours lost to industrial accidents. The null and alternative hypotheses were H0: μ = 0 H1: μ < 0 with σ = 6, α = .10, n = 50, and μ =

> Suppose that in Example 11.1 we wanted to determine whether there was sufficient evidence to conclude that the new system would not be costeffective. Set up the null and alternative hypotheses and discuss the consequences of Type I and Type II errors. Co

> Draw the operating characteristic curve for n = 10, 50, and 100 for the following test: H0: μ = 400 H1: μ > 400 α = .05, σ = 50

> For the test of hypothesis H0: μ = 1,000 H1: μ ≠ 1,000 α = .05, σ = 200 draw the operating characteristic curve for n = 25, 100, and 200.

> 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 = 1000 H1: μ ≠ 1000 σ = 200, n = 100, x = 980, α = .01

> Several years ago, in a high-profile case, a defendant was acquitted in a double-murder trial but was subsequently found responsible for the deaths in a civil trial. (Guess the name of the defendant—the answer is in Appendix C.) In a civil trial the plai

> Many Americans contributed to their 401k investment accounts. An economist wanted to determine how well these investments performed. A random sample of Americans with 401k investments were surveyed and asked to report the total amount invested. Can we in

> You are contemplating a Ph.D. in business or economics. If you succeed, a life of fame, fortune, and happiness awaits you. If you fail, you’ve wasted 5 years of your life. Should you go for it?

> A survey of American consumers asked respondents to report the amount of money they spend on bakery products in a typical month. If we assume that the population standard deviation is $5, can we conclude at the 10% significance level that the mean monthl

> An economist surveyed homeowners in a large city to determine the percentage increase in their heating bills over the last 5 years. The economist particularly wanted to know if there was enough evidence to infer that heating cost increases were greater t

> The current no-smoking regulations in office buildings require workers who smoke to take breaks and leave the building in order to satisfy their habits. A study indicates that such workers average 32 minutes per day taking smoking breaks. The standard de

> The golf professional at a private course claims that members who have taken lessons from him lowered their handicap by more than five strokes. The club manager decides to test the claim by randomly sampling 25 members who have had lessons and asking eac

> Many Alpine ski centers base their projections of revenues and profits on the assumption that the average Alpine skier skis four times per year. To investigate the validity of this assumption, a random sample of 63 skiers is drawn and each is asked to re

> A fast-food franchiser is considering building a restaurant at a certain location. Based on financial analyses, a site is acceptable only if the number of pedestrians passing the location averages more than 100 per hour. The number of pedestrians observe

> For the past few years, the number of customers of a drive-up bank in New York has averaged 20 per hour, with a standard deviation of 3 per hour. This year, another bank 1 mile away opened a drive-up window. The manager of the first bank believes that th

> You are the pilot of a jumbo jet. You smell smoke in the cockpit. The nearest airport is less than 5 minutes away. Should you land the plane immediately?

> An automotive expert claims that the large number of self-serve gasoline stations has resulted in poor automobile maintenance, and that the average tire pressure is more than 4 pounds per square inch (psi) below its manufacturer’s specification. As a qui

> A highway patrol officer believes that the average speed of cars traveling over a certain stretch of highway exceeds the posted limit of 55 mph. The speeds of a random sample of 200 cars were recorded. Do these data provide sufficient evidence at the 1%

> It is the responsibility of the federal government to judge the safety and effectiveness of new drugs. There are two possible decisions: approve the drug or disapprove the drug.

> In an attempt to reduce the number of person-hours lost as a result of industrial accidents, a large production plant installed new safety equipment. In a test of the effectiveness of the equipment, a random sample of 50 departments was chosen. The numbe

> Past experience indicates that the monthly long-distance telephone bill is normally distributed with a mean of $17.85 and a standard deviation of $3.87. After an advertising campaign aimed at increasing long-distance telephone usage, a random sample of 2

> A dean of a business school claims that the Graduate Management Admission Test (GMAT) scores of applicants to the school’s MBA program have increased during the past 5 years. Five years ago, the mean and standard deviation of GMAT scores of MBA applicant

> In the midst of labor–management negotiations, the president of a company argues that the company’s blue-collar workers, who are paid an average of $30,000 per year, are well paid because the mean annual income of all blue-collar workers in the country i

> A manufacturer of lightbulbs advertises that, on average, its long-life bulb will last more than 5,000 hours. To test the claim, a statistician took a random sample of 100 bulbs and measured the amount of time until each bulb burned out. If we assume tha

> Spam e-mail has become a serious and costly nuisance. An office manager believes that the average amount of time spent by office workers reading and deleting spam exceeds 25 minutes per day. To test this belief, he takes a random sample of 18 workers and

> A machine that produces ball bearings is set so that the average diameter is .50 inch. A sample of 10 ball bearings was measured, with the results shown here. Assuming that the standard deviation is .05 inch, can we conclude at the 5% significance level

> The owner of a public golf course is concerned about slow play, which clogs the course and results in selling fewer rounds. She believes the problem lies in the amount of time taken to sink putts on the green. To investigate the problem, she randomly sam

> You are faced with two investments. One is very risky, but the potential returns are high. The other is safe, but the potential is quite limited. Pick one.

> A random sample of 12 second-year university students enrolled in a business statistics course was drawn. At the course’s completion, each student was asked how many hours he or she spent doing homework in statistics. The data are listed here. It is know

> The club professional at a difficult public course boasts that his course is so tough that the average golfer loses a dozen or more golf balls during a round of golf. A dubious golfer sets out to show that the pro is fibbing. He asks a random sample of 1

> A random sample of 18 young adult men (20â30 years old) was sampled. Each person was asked how many minutes of sports he watched on television daily. The responses are listed here. It is known that Ï = 10. Test to determine a

> A business student claims that, on average, an MBA student is required to prepare more than five cases per week. To examine the claim, a statistics professor asks a random sample of 10 MBA students to report the number of cases they prepare weekly. The r

> Refer to Example 11.2. Create a table that shows the effect on the test statistic and the p-value of changing the value of the sample mean. Use x = 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, and 19.0. Data from Example 11.2: FIGURE 11.8 Samplin

> Redo Example 11.2 with a. σ = 2 b. σ = 10 c. What happens to the test statistic and the p-value when σ increases?

> For the SSA example, create a table that shows the effect on the test statistic and the p-value of decreasing the value of the sample mean. Use x = 22.0, 21.8, 21.6, 21.4, 21.2, 21.0, 20.8, 20.6, and 20.4.

> Redo the SSA example with a. σ = 3 b. σ = 12 c. Discuss the effect on the test statistic and the p-value when σ increases.

> You are the centerfielder of the New York Yankees. It is the bottom of the ninth inning of the seventh game of the World Series. The Yanks lead by 2 with 2 outs and men on second and third. The batter is known to hit for high average and runs very well b

> While conducting a test to determine whether a population mean is less than 900, you find that the sample mean is 1,050. a. Can you make a decision on this information alone? Explain. b. If you did calculate the p-value, would it be smaller or larger tha

> Redo Example 11.1 with a. Ï = 35 b. Ï = 100 c. Describe the effect on the test statistic and the p-value when Ï increases. Data from Example 11.1: FIGURE 11.1 Sampling Distribution for Example 11.1 A-170 Rejection re

> Redo Example 11.1 with a. n = 200 b. n = 100 c. Describe the effect on the test statistic and the p-value when n increases. Data from Example 11.1: FIGURE 11.1 Sampling Distribution for Example 11.1 A-170 Rejection region

> a. Calculate the p-value of the test described here. H0: μ = 60 H1: μ > 60 x = 72, n = 25, σ = 20 b. Repeat part (a) with x = 68. c. Repeat part (a) with x = 64. d. Describe the effect on the test statistic and the p-value of the test when the value of x

> a. Find the p-value of the following test given that x = 990, n = 100, and σ = 25. H0: μ = 1000 H1: μ < 1000 b. Repeat part (a) with σ = 50. c. Repeat part (a) with σ = 100. d. Describe what happens to the value of the test statistic and its p-value when

> a. Test these hypotheses by calculating the p-value given that x = 99, n = 100, and σ = 8. H0: μ = 100 H1: μ ≠ 100 b. Repeat part (a) with n = 50. c. Repeat part (a) with n = 20. d. What is the effect on the value of the test statistic and the p-value of

> a. Given the following hypotheses, determine the p-value when x = 21, n = 25, and σ = 5. H0: μ = 20 H1: μ ≠ 20 b. Repeat part (a) with x = 22. c. Repeat part (a) with x = 23. d. Describe what happens to the value of the test statistic and its p-value whe

> a. A statistics practitioner formulated the following hypotheses H0: μ = 200 H1: μ < 200 and learned that x = 190, n = 9, and σ = 50 Compute the p-value of the test. b. Repeat part (a) with σ = 30. c. Repeat part (a) with σ = 10. d. Discuss what happens

> You are conducting a test to determine whether there is enough statistical evidence to infer that a population mean is greater than 100. You discover that the sample mean is 95. a. Is it necessary to do any further calculations? Explain. b. If you did ca

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is not equal to –5. σ = 5, n = 25, x = − 4.0

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is not equal to 0. σ = 50, n = 90, x = − 5.5.

> Repeat Exercise 9.15 with n = 25. Data from Exercise 9.15: A sample of n = 16 observations is drawn from a normal population with μ = 1,000 and σ = 200. Find the following. a. P(X > 1,050) b. P(X < 960) c. P(X > 1,100)

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is less than 0. σ = 25, n = 400, x = − 2.3

> A sample of n = 16 observations is drawn from a normal population with μ = 1,000 and σ = 200. Find the following. a. P(X > 1,050) b. P(X < 960) c. P(X > 1,100)

> Refer to Exercise 9.13. Suppose that the population is not normally distributed. Does this change your answer? Explain. Data from Exercise 9.13: A normally distributed population has a mean of 40 and a standard deviation of 12. What does the central lim

> A normally distributed population has a mean of 40 and a standard deviation of 12. What does the central limit theorem say about the sampling distribution of the mean if samples of size 100 are drawn from this population?

> Refer to Example 3.2. From the histogram for investment A, estimate the following probabilities. a. P(X > 45) b. P(10 c. P(X d. P(35 Data from Example 3.2: Histogram of Returns on InvestmentA 18 16 2 -30 -15 15 30 45 60 76 Returns kouenbay

> The weekly output of a steel mill is a uniformly distributed random variable that lies between 110 and 175 metric tons. a. Compute the probability that the steel mill will produce more than 150 metric tons next week. b. Determine the probability that the

> The demand for a daily newspaper at a newsstand at a busy intersection is known to be normally distributed with a mean of 150 and a standard deviation of 25. How many newspapers should the newsstand operator order to ensure that he runs short on no more

> A retailer of computing products sells a variety of computer-related products. One of his most popular products is an HP laser printer. The average weekly demand is 200. Lead time for a new order from the manufacturer to arrive is 1 week. If the demand f

> According to the Statistical Abstract of the United States, 2012 (Table 721), the mean family net worth of families whose head is between 35 and 44 years old is approximately $325,600. If family net worth is normally distributed with a standard deviation

> The daily withdrawals from an ATM located at a service station is normally distributed with a mean of $50,000 and a standard deviation of $8,000. The operator of the ATM puts $64,000 in cash at the beginning of the day. What is the probability that the A

> Mensa is an organization whose members possess IQs that are in the top 2% of the population. It is known that IQs are normally distributed with a mean of 100 and a standard deviation of 16. Find the minimum IQ needed to be a Mensa member.

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is greater than 0. σ = 10, n = 100, x = 1.5

> The final marks in a statistics course are normally distributed with a mean of 70 and a standard deviation of 10. The professor must convert all marks to letter grades. She decides that she wants 10%A’s, 30%B’s, 40%C’s, 15%D’s, and 5%F’s. Determine the c

> How much money does a typical family of four spend at a McDonald’s restaurant per visit? The amount is a normally distributed random variable with a mean of $16.40 and a standard deviation of $2.75. a. Find the probability that a family of four spends le

> It is said that sufferers of a cold virus experience symptoms for 7 days. However, the amount of time is actually a normally distributed random variable whose mean is 7.5 days and whose standard deviation is 1.2 days. a. What proportion of cold sufferers

> Because of the relatively high interest rates, most consumers attempt to pay off their credit card bills promptly. However, this is not always possible. An analysis of the amount of interest paid monthly by a bank’s Visa cardholders reveals that the amou

> Battery manufacturers compete on the basis of the amount of time their products last in cameras and toys. A manufacturer of alkaline batteries has observed that its batteries last for an average of 26 hours when used in a toy racing car. The amount of ti

> A golfer playing a new course encounters a hole that requires a drive of 145 yards to successfully clear a pond. She knows that her drives are normally distributed with a mean of 155 yards and a standard deviation of 9 yards. What is the probability that

> The mean monthly income of graduates of professional and Ph.D. degrees is $6,000 according to a recent PEW Research Center survey. If these incomes are normally distributed with a standard deviation of $1,200, a. What proportion of incomes is greater tha

> Refer to Exercise 8.57. The manufacturer wants to provide guidelines to potential customers advising them of the minimum number of pages they can expect from each cartridge. How many pages should it advertise if the company wants to be correct 99% of the

> The number of pages printed before replacing the cartridge in a laser printer is normally distributed with a mean of 11,500 pages and a standard deviation of 800 pages. A new cartridge has just been installed. a. What is the probability that the printer

> The amount of time devoted to studying statistics each week by students who achieve a grade of A in the course is a normally distributed random variable with a mean of 7.5 hours and a standard deviation of 2.1 hours. a. What proportion of A student’s stu

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is greater than 7.5. σ = 1.5, n = 30, x = 8.5

> Refer to Exercise 8.54. Find the amount of sleep that is exceeded by only 25% of students. Data from Exercise 8.54: University and college students average 7.2 hours of sleep per night, with a standard deviation of 40 minutes. If the amount of sleep is

> University and college students average 7.2 hours of sleep per night, with a standard deviation of 40 minutes. If the amount of sleep is normally distributed, what proportion of university and college students sleep for more than 8 hours?

> Refer to Exercise 8.52. Find the probability of these events. a. A 2-year-old child is taller than 36 inches. b. A 2-year-old child is shorter than 34 inches. c. A 2-year-old child is between 30 and 33 inches tall. Data from Exercise 8.52: The heights o

> The heights of 2-year-old children are normally distributed with a mean of 32 inches and a standard deviation of 1.5 inches. Pediatricians regularly measure the heights of toddlers to determine whether there is a problem. There may be a problem when a ch

> The top-selling Red and Voss tire is rated 70,000 miles, which means nothing. In fact, the distance the tires can run until they wear out is a normally distributed random variable with a mean of 82,000 miles and a standard deviation of 6,400 miles. a. Wh

> Economists frequently make use of quintiles (i.e., the 20th, 40th, 60th, and 80th percentiles) particularly when discussing incomes. Suppose that in a large city household income are normally distributed with a mean of $50,000 and a standard deviation of

> Exercise 4.67 addressed the problem of setting an appropriate speed limit on highways. Automotive experts believe that the “correct” speed is the 85th percentile. Suppose that the speeds on a highway are normally distributed with a mean of 68 and a stand

> The Tesla Model S 85D is an electric car that the manufacturer claims can travel 270 miles on a single charge. However, the actual distance depends on a number of factors including speed and whether the car is driven in the city or on highways. Suppose t

> According to a PEW Research Center survey, the mean student loan at graduation is $25,000. Suppose that student loans are normally distributed with a standard deviation of $5,000. A graduate with a student loan is selected at random. Find the following p

> SAT scores are normally distributed with a mean of 1,000 and a standard deviation of 300. Find the quartiles.

> Calculate the p-value of the test to determine that there is sufficient evidence to infer each research objective. Research objective: The population mean is not equal to 1,500. σ = 220, n = 125, x = 1525

> Refer to Exercise 8.44. If we wanted to be sure that 98% of all bulbs last longer than the advertised figure, what figure should be advertised? Data from Exercise 8.44: The lifetimes of lightbulbs that are advertised to last for 5,000 hours are normally

Question: Redo Example 11.2 with a. n =

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