If you use a 0.10 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting a null hypothesis that the population mean equals 500 if you use the Z test?
> Assuming that the population is normally distributed, construct a 95% confidence interval for the population mean, based on the following sample of size n = 7: 1 2 3 4 5 6 20 Change the value of 20 to 7 and recalculate the confidence interval. Using thes
> Financial institutions utilize prediction models to predict bankruptcy. One such model is the Altman Z-score model, which uses multiple corporate income and balance sheet values to measure the financial health of a company. If the model predicts a low Z-
> In Problem 9.36, what is your statistical decision if you test the null hypothesis at the 0.05 level of significance? Problem 9.36: In a one-tail hypothesis test where you reject H0 only in the upper tail, what is the p-value if ZSTAT = +2.00?
> In hypothesis testing, the common level of significance is α = 0.05. Some might argue for a level of significance greater than 0.05. Suppose that web designers tested the proportion of potential web page visitors with a preference for a new web design ov
> What is the five-step p-value approach to hypothesis testing?
> What is the six-step critical value approach to hypothesis testing?
> How can a confidence interval estimate for the population mean provide conclusions for the corresponding two-tail hypothesis test for the population mean?
> What is meant by a p-value?
> What is the difference between a one-tail test and a two-tail test?
> What is meant by the power of a test?
> What is the difference between a Type I error and a Type II error?
> What is the difference between a null hypothesis, H0, and an alternative hypothesis, H1?
> Assuming that the population is normally distributed, construct a 95% confidence interval estimate for the population mean for each of the following samples: Sample A: 1 1 1 1 8 8 8 8 Sample B: 1 2 3 4 5 6 7 8 Explain why these two samples produce diff
> In a one-tail hypothesis test where you reject H0 only in the upper tail, what is the p-value if ZSTAT = +2.00?
> Actuation Consulting conducted a global survey of product teams with the goal of better understanding the dynamics of product team performance and uncovering the practices that make these teams successful. Having a clear definition of “done” is a basic e
> A cellphone provider has the business objective of wanting to determine the proportion of subscribers who would upgrade to a new cellphone with improved features if it were made available at a substantially reduced cost. Data are collected from a random
> What are companies’ biggest obstacles to attracting the best talent? Of 703 surveyed U.S. and Canadian talent acquisition professionals, 464 reported that competition for talent is the biggest obstacle at their company. Source: U.S. and Canadian Recruiti
> One of the issues facing organizations is increasing diversity throughout an organization. One of the ways to evaluate an organization’s success at increasing diversity is to compare the percentage of employees in the organization in a particular positio
> The worldwide market share for the Chrome web browser was 56.43% in a recent month. Source: Data extracted from netmarketshare.com. Suppose that you decide to select a sample of 100 students at your university and you find that 60 use the Chrome web brow
> According to a recent National Association of Colleges and Employers (NACE) report, 44% of college students who had unpaid internships received full-time job offers post-graduation compared to 72% of college students who had paid internships. Source: Dat
> In Problems 9.52 and 9.53, suppose you are testing the null hypothesis H0: π = 0.20 against the two-tail alternative hypothesis H1: π ≠ 0.20 and you choose the level of significance α = 0.05. What is your statistical decision? Problem 9.53: In Problem
> In Problem 9.52, if the null hypothesis is that 20% of the items in the population are defective, what is the value of ZSTAT? Problem 9.52: If, in a random sample of 400 items, 88 are defective, what is the sample proportion of defective items?
> The following data (in Drink ) represent the amount of soft drink filled in a sample of 50 consecutive 2-liter bottles. The results, listed horizontally in the order of being filled, were: 2.109 2.086 2.066 2.075 2.065 2.057 2.052 2.044 2.036 2.038 2.03
> An insurance company has the business objective of reducing the amount of time it takes to approve applications for life insurance. The approval process consists of underwriting, which includes a review of the application, a medical information bureau ch
> The file FastFood contains the amount that a sample of fifteen customers spent for lunch ($) at a fast-food restaurant: 7.42 6.29 5.83 6.50 8.34 9.51 7.10 6.80 5.90 4.89 6.50 5.52 7.90 8.30 9.60 a. At the 0.05 level of significance, is there evidence tha
> If, in a random sample of 400 items, 88 are defective, what is the sample proportion of defective items?
> The U.S. Department of Transportation requires tire manufacturers to provide performance information on tire sidewalls to help prospective buyers make their purchasing decisions. One very important piece of information is the tread wear index, which indi
> A marketing researcher wants to estimate the mean amount spent per year ($) on Amazon.com by Amazon Prime member shoppers. Suppose a random sample of 100 Amazon Prime member shoppers who recently made a purchase on Amazon.com yielded a mean amount spent
> A manufacturer of chocolate candies uses machines to package candies as they move along a filling line. Although the packages are labeled as 8 ounces, the company wants the packages to contain a mean of 8.17 ounces so that virtually none of the packages
> You are the manager of a restaurant for a fast-food franchise. Last month, the mean waiting time at the drive-through window for branches in your geographic region, as measured from the time a customer places an order until the time the customer receives
> A bottled water distributor wants to estimate the amount of water contained in 1-gallon bottles purchased from a nationally known water bottling company. The water bottling company’s specifications state that the standard deviation of the amount of water
> The population mean waiting time to check out of a supermarket has been 4 minutes. Recently, in an effort to reduce the waiting time, the supermarket has experimented with a system in which infrared cameras use body heat and in-store software to determin
> We Are Social and Hootsuite reported that the typical American spends 2.02 hours (121 minutes) per day accessing the Internet via mobile devices. Source: Digital in 2017 Global Overview, available at bit.ly/2jXeS3F. In order to test the validity of this
> Suppose that in Problem 9.16, the standard deviation is 0.012 gallon. a. Repeat (a) through (d) of Problem 9.16, assuming a standard deviation of 0.012 gallon. b. Compare the results of (a) to those of Problem 9.16.
> A bottled water distributor wants to determine whether the mean amount of water contained in 1-gallon bottles purchased from a nationally known water bottling company is actually 1 gallon. You know from the water bottling company specifications that the
> Suppose that in Problem 9.14, the standard deviation is 500 hours. a. Repeat (a) through (d) of Problem 9.14, assuming a standard deviation of 500 hours. b. Compare the results of (a) to those of Problem 9.14.
> The quality-control manager at a light emitting diode (LED) factory needs to determine whether the mean life of a large shipment of LEDs is equal to 50,000 hours. The population standard deviation is 1,500 hours. A random sample of 64 LEDs indicates a sa
> Do business seniors at your school prepare for class more than, less than, or about the same as business seniors at other schools? The National Survey of Student Engagement (NSSE) annual results, available at bit.ly/1j3Ob7N, found that business seniors s
> As a result of complaints from both students and faculty about lateness, the registrar at a large university is ready to undertake a study to determine whether the scheduled break between classes should be changed. Until now, the registrar has believed t
> Many consumer groups feel that the U.S. Food and Drug Administration (FDA) drug approval process is too easy and, as a result, too many drugs are approved that are later found to be unsafe. On the other hand, a number of industry lobbyists have pushed fo
> You are working as an assistant to the dean of institutional research at your university. The dean wants to survey members of the alumni association who obtained their baccalaureate degrees five years ago to learn what their starting salaries were in the
> Suppose the defendant in Problem 9.9 is presumed guilty until proven innocent. How do the null and alternative hypotheses differ from those in Problem 9.9? What are the meanings of the risks of committing either a Type I or Type II error here?
> Determine the critical value of t in each of the following circumstances: a. 1 - α = 0.95, n = 10 b. 1 - α = 0.99, n = 10 c. 1 - α = 0.95, n = 32 d. 1 - α = 0.95, n = 65 e. 1 - α = 0.90, n = 16
> In the U.S. legal system, a defendant is presumed innocent until proven guilty. Consider a null hypothesis, H0, that a defendant is innocent, and an alternative hypothesis, H1, that the defendant is guilty. A jury has two possible decisions: Convict the
> What is the p-value if, in a two-tail hypothesis test, ZSTAT = -1.38?
> In Problem 9.6, what is your statistical decision if you test the null hypothesis at the 0.10 level of significance? Problem 9.6: What is the p-value if, in a two-tail hypothesis test, ZSTAT = +2.00?
> What is the p-value if, in a two-tail hypothesis test, ZSTAT = +2.00?
> What is your decision in Problem 9.4 if ZSTAT = -2.61? Problem 9.4: If you use a 0.01 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting H0 :μ = 12.5 if you use the Z test?
> If you use a 0.01 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting H0 :μ = 12.5 if you use the Z test?
> If you use a 0.05 level of significance in a two-tail hypothesis test, what decision will you make if ZSTAT = +2.21?
> If you use a 0.05 level of significance in a two-tail hypothesis test, what decision will you make if ZSTAT = -0.76?
> Consider the confidence interval estimate discussed in Problem 8.5. Suppose the population mean time spent on the site is 36 minutes a day. Is the confidence interval estimate stated in Problem 8.5 correct? Explain.
> A survey of nonprofit organizations showed that online fundraising has increased in the past year. Based on a random sample of 133 nonprofits, the mean one-time gift donation resulting from email outreach in the past year was $87. Assume that the sample
> Referring to the results in Problem 8.66 concerning the answer time of calls, write a report that summarizes your conclusions.
> The manufacturer of Boston and Vermont asphalt shingles knows that product weight is a major factor in a customer’s perception of quality. The last stage of the assembly line packages the shingles before they are placed on wooden pallets. Once a pallet i
> The manufacturer of Boston and Vermont asphalt shingles knows that product weight is a major factor in a customer’s perception of quality. The last stage of the assembly line packages the shingles before they are placed on wooden pallets. Once a pallet i
> Call centers today play an important role in managing day-today business communications with customers. It’s important, therefore, to monitor a comprehensive set of metrics, which can help businesses understand the overall performance of a call center. O
> A quality characteristic of interest for a tea-bag-filling process is the weight of the tea in the individual bags. In this example, the label weight on the package indicates that the mean amount is 5.5 grams of tea in a bag. If the bags are underfilled,
> Claims fraud (illegitimate claims) and buildup (exaggerated loss amounts) continue to be major issues of concern among automobile insurance companies. Fraud is defined as specific material misrepresentation of the facts of a loss; buildup is defined as t
> The manufacturer of Ice Melt claims that its product will melt snow and ice at temperatures as low as 0° Fahrenheit. A representative for a large chain of hardware stores is interested in testing this claim. The chain purchases a large shipment of 5-poun
> You are the manager of a restaurant that delivers pizza to college dormitory rooms. You have just changed your delivery process in an effort to reduce the mean time between the order and completion of delivery from the current 25 minutes. A sample of 36
> Suppose that you are going to collect a set of data, either from an entire population or from a random sample taken from that population. a. Which statistical measure would you compute first: the mean or the standard deviation? Explain. b. What does your
> How do smartphone owners use their smartphones when shopping in a grocery store? A sample of 731 smartphone owners in the United States revealed that 358 use their smartphone to access digital coupons, 355 look up recipes, 234 read reviews of products an
> A GlobalWebIndex study noted the percentage of Internet users that owned various devices. Suppose that a survey of 1,000 Internet users found that 840 own a PC/laptop, 910 own a smartphone, 500 own a tablet, and 100 own a smart watch. Source: Data extrac
> Why is the sample size needed to determine the proportion smaller when the population proportion is 0.20 than when the population proportion is 0.50?
> Why is it true that for a given sample size, n, an increase in confidence is achieved by widening (and making less precise) the confidence interval?
> When should you use the t distribution to develop the confidence interval estimate for the mean?
> Patient waiting is a common phenomenon in the doctor’s waiting room. One acceptable standard of practice states that waiting time for patients to be seen by the first provider in hospital outpatient and public health clinics should be less than 30 minute
> Why can you never really have 100% confidence of correctly estimating the population characteristic of interest?
> A market researcher selects a simple random sample of n = 100 Twitter users from a population of over 100 million Twitter registered users. After analyzing the sample, she states that she has 95% confidence that the mean time spent on the site per day is
> Personal data is the new currency of the digital economy. How do consumers feel about sharing personal data with their communication service providers (CSPs)? A recent IBM report highlights that 40% of 18- to 25-year-old consumers are comfortable sharing
> Cybersecurity is a critical business issue that demands the attention of business and IT executives. According to a study released by PwC, 38% of surveyed business and IT executives reported phishing scams at their institutions. Source: Data extracted f
> In a study of 443 nonprofits nationwide, 130 indicated that the greatest diversity staffing challenge they face is retaining younger staff (those under 30). Source: Data extracted from “2016 Nonprofit Employment Practices Survey,” Nonprofit HR, 2016, bi
> A Federal Reserve Bank of Atlanta report looks at what strategies and measures financial institutions are pursuing to provide mobile financial services to their customers. In response to a survey question about barriers hindering greater consumer adoptio
> What does brand loyalty mean to consumers? According to a Rare research report, 20% of consumers associate trust with brand loyalty. Source: Data extracted from “Redefining Loyalty,” Rare, 2016, bit.ly/2solA40. a. To conduct a follow-up study that would
> A growing niche in the restaurant business is gourmet-casual breakfast, lunch, and brunch. Chains in this group include Panera Bread. Suppose that the mean per-person check for breakfast at Panera Bread is approximately $9.50. a. Assuming a standard devi
> An advertising media analyst wants to estimate the mean amount of time that consumers spend with digital media daily. From past studies, the standard deviation is estimated as 45 minutes. a. What sample size is needed if the media analyst wants to be 90%
> An advertising media analyst wants to estimate the mean weekly amount of time consumers spend watching television daily. Based on previous studies, the standard deviation is assumed to be 20 minutes. The media analyst wants to estimate, with 99% confiden
> CarMD reports that after two years of flat U.S. car repair costs, 2016 saw an increase. One of the most common problems that trigger the “check engine” light is the catalytic converter. Repairing the catalytic converter had a mean repair cost of $1,190 i
> If the inspection division of a county weights and measures department wants to estimate the mean amount of soft-drink fill in 2-liter bottles to within ±0.01 liter with 95% confidence and also assumes that the standard deviation is 0.05 liter, what samp
> If a light bulb manufacturing company wants to estimate, with 95% confidence, the mean life of light emitting diode (LED) light bulbs to within ±400 hours and also assumes that the population standard deviation is 1,500 hours, how many LED light bulbs ne
> Is it true in Example 8.1 on page 280 that you do not know for sure whether the population mean is between 366.33 and 372.21 grams? Explain.
> If the manager of a bottled water distributor wants to estimate, with 95% confidence, the mean amount of water in a 1-gallon bottle to within ±0.004 gallon and also assumes that the standard deviation is 0.02 gallon, what sample size is needed?
> A survey is planned to determine the mean annual family medical expenses of employees of a large company. The management of the company wishes to be 95% confident that the sample mean is correct to within ±$50 of the population mean annual family medical
> If you want to be 95% confident of estimating the population proportion to within a sampling error of ±0.02 and there is historical evidence that the population proportion is approximately 0.40, what sample size is needed?
> If you want to be 99% confident of estimating the population proportion to within a sampling error of ±0.04, what sample size is needed?
> If you want to be 99% confident of estimating the population mean to within a sampling error of ±20 and the standard deviation is assumed to be 100, what sample size is required?
> If you want to be 95% confident of estimating the population mean to within a sampling error of ±5 and the standard deviation is assumed to be 15, what sample size is required?
> What business, economic, policy, and environmental threats to organization growth are CEOs extremely concerned about? In a survey by PricewaterhouseCoopers (PwC), 57 of 114 U.S. CEOs are extremely concerned about cyber threats, and 22 are extremely conce
> The Washington Metropolitan Area Transit Authority has set a bus fleet reliability goal of 8,000 bus miles. Bus reliability is measured specifically as the number of bus miles traveled before a mechanical breakdown that requires the bus to be removed fro
> A Pew Research Center survey of 4,787 adults found that 4,178 had bought something online. Of these online shoppers, 789 are weekly online shoppers. a. Construct a 95% confidence interval estimate of the population proportion of adults who had bought so
> In a survey of 823 human resource professionals concerning challenges they faced in the workplace, 329 said that employee retention/turnover was an important challenge and 181 said that employee satisfaction was an important challenge. Source: Data extra
> What do you value most when shopping in a retail store? According to a TimeTrade survey, 26% of consumers value personalized experience most. Source: Data extracted from “The State of Retail, 2017,” TimeTrade, bit.ly/2rFGf7o. a. Suppose that the survey h
> Why is it not possible in Example 8.1 on page 280 to have 100% confidence? Explain.
> In a survey of 1,003 adults concerning complaints about restaurants, 732 complained about dirty or ill-equipped bathrooms and 381 complained about loud or distracting diners at other tables. Source: Data extracted from “The Gripe-O-Meter Restaurants,” Co
> A cellphone provider has the business objective of wanting to estimate the proportion of subscribers who would upgrade to a new cellphone with improved features if it were made available at a substantially reduced cost. Data are collected from a random s
> If n = 400 and X = 25, construct a 99% confidence interval estimate for the population proportion.
> If n = 200 and X = 50, construct a 95% confidence interval estimate for the population proportion.
> One operation of a mill is to cut pieces of steel into parts that are used in the frame for front seats in an automobile. The steel is cut with a diamond saw, and the resulting parts must be cut to be within {0.005 inch of the length specified by the aut
> The file MobileCommerce contains mobile commerce penetration values (the percentage of the country population that bought something online via a mobile phone in the past month) for twenty-eight of the world’s economies: 23 27 26 25 40 19 26 36 23 33 23
