Questions and Answers of Statistical Techniques in Business

Police Chief Edward Wilkin of River City reports 500 traffic citations were issued last month. A sample of 35 of these citations showed the mean amount of the fine was $54, with a standard deviation
A random sample of 85 group leaders, supervisors, and similar personnel at General Motors revealed that, on average, they spent 6.5 years in a particular job before being promoted. The standard
There are 300 welders employed at Maine Shipyards Corporation. A sample of 30 welders revealed that 18 graduated from a registered welding course. Construct the 95% confidence interval for the
The attendance at the Savannah Colts minor league baseball game last night was 400. A random sample of 50 of those in attendance revealed that the mean number of soft drinks consumed per person was
A large on-demand, video streaming company is designing a large-scale survey to determine the mean amount of time corporate executives watch on-demand television. A small pilot survey of 10
A population’s standard deviation is 10. We want to estimate the population mean within 2, with a 95% level of confidence. How large a sample is required?
The Columbus, Ohio Area Chamber of Commerce wants to estimate the mean time workers who are employed in the downtown area spend getting to work. A sample of 15 workers reveals the following number of
Merrill Lynch Securities and Health Care Retirement Inc. are two large employers in downtown Toledo, Ohio. They are considering jointly offering child care for their employees. As a part of the
Dr. Patton is a professor of English. Recently she counted the number of misspelled words in a group of student essays. She noted the distribution of misspelled words per essay followed the normal
Bob Nale is the owner of Nale’s Quick Fill. Bob would like to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons sold follows the normal
Refer to the previous exercise. Instead of 49, suppose that 64 Americans were surveyed about their weekly expenditures on coffee. Assume the sample mean remained the same.a. What is the 95%
A sample of 81 observations is taken from a normal population with a standard deviation of 5. The sample mean is 40. Determine the 95% confidence interval for the population mean.
A sample of 49 observations is taken from a normal population with a standard deviation of 10. The sample mean is 55. Determine the 99% confidence interval for the population mean.
Refer to the Lincolnville School District bus data. Information provided by manufacturers of school buses suggests the mean maintenance cost per year is $4,400 per bus with a standard deviation of
Crossett Trucking Company claims that the mean weight of its delivery trucks when they are fully loaded is 6,000 pounds and the standard deviation is 150 pounds. Assume that the opulation
In the United States, the mean age of men when they marry for the first time follows the normal distribution with a mean of 29 years. The standard deviation of the distribution is 2.5 years. For a
Information from the American Institute of Insurance indicates the mean amount of life insurance per household in the United States is $165,000. This distribution follows the normal distribution with
Majesty Video Production Inc. wants the mean length of its advertisements to be 30 seconds. Assume the distribution of ad length follows the normal distribution with a population standard deviation
In establishing warranties on HDTVs, the manufacturer wants to set the limits so that few will need repair at the manufacturer’s expense. On the other hand, the warranty period must be long enough
Refer to the Lincolnville School District bus data.a. Refer to the maintenance cost variable. The mean maintenance cost for last year is $4,552 with a standard deviation of $2332. Estimate the number
Management at Gordon Electronics is considering adopting a bonus system to increase production. One suggestion is to pay a bonus on the highest 5% of production based on past experience. Past records
The manufacturer of a laser printer reports the mean number of pages a cartridge will print before it needs replacing is 12,200. The distribution of pages printed per cartridge closely follows the
In economic theory, a “hurdle rate” is the minimum return that a person requires before he or she will make an investment. A research report says that annual returns from a specific class of
The SAT Reasoning Test is perhaps the most widely used standardized test for college admissions in the United States. Scores are based on a normal distribution with a mean of 1500 and a standard
Given the following hypotheses:H0: μ = 400H1: μ ≠ 400A random sample of 12 observations is selected from a normal population. The sample mean was 407 and the sample standard deviation 6. Using
The mean income per person in the United States is $50,000, and the distribution of incomes follows a normal distribution. A random sample of 10 residents of Wilmington, Delaware, had a mean of
Refer to the following table and the example just completed. With n = 100, Ïƒ = 400, xÌ…c= 9,922 and Î¼1= 9,880, verify that the probability of a Type II error is
Refer to the following table and the example just completed. With n = 100, Ïƒ = 400, xÌ…c= 10,078, and Î¼1 = 10,100, verify that the probability of a Type II
The management of KSmall Industries is considering a new method of assembling a computer. The current assembling method requires a mean time of 60 minutes with a standard deviation of 2.7 minutes.
A recent national survey found that parents read an average (mean) of 10 books per month to their children under five years old. The population standard deviation is 5. The distribution of books read
A recent survey by nerdwallet.com indicated Americans paid a mean of $6,658 interest on credit card debt in 2017. A sample of 12 households with children revealed the follow mounts. At the .05
A recent article in The Wall Street Journal reported that the home equity loan rate is now less than 4%. A sample of eight small banks in the Midwest revealed the following home equity loan rates (in
The number of €œdestination weddings€ has skyrocketed in recent years. For example, many couples are opting to have their weddings in the Caribbean. A Caribbean vacation resort
The North Valley Real Estate data reports information on the homes sold last year.Adam Marty recently joined North Valley Real Estate and was assigned twenty homes to market and show. When he was
Refer to the Baseball 2016 data, which report information on the 30 Major League Baseball teams for the 2016 season.a. Conduct a test of hypothesis to determine whether the mean salary of the teams
Do married and unmarried women spend the same amount of time per week using Facebook? A random sample of 45 married women who use Facebook spent an average of 3.0 hours per week on this social media
Mary Jo Fitzpatrick is the vice president for Nursing Services at St. Luke€™s Memorial Hospital. Recently she noticed in the job postings for nurses that those that are unionized seem to
Listed below are the 25 players on the opening-day roster of the 2016 New York Yankees Major League Baseball team, their salaries, and fielding positions.Sort the players into two groups, all
The Tampa Bay (Florida) Area Chamber of Commerce wanted to know whether the mean weekly salary of nurses was larger than that of school teachers. To investigate, they collected the following
The probability that the cause and the cure for all cancers will be discovered before the year 2020 is .20. What viewpoint of probability does this statement illustrate?
The number of times a particular event occurred in the past is divided by the number of occurrences. What is this approach to probability called?
The marketing research department at Pepsico plans to survey teenagers about a newly developed soft drink. Each will be asked to compare it with his or her favorite soft drink.a. What is the
Sam Snead’s restaurant in Conway, South Carolina, offers an early bird special from 4–6 pm each week day evening. If each patron selects a Starter Selection (4 options), an Entrée (8 options),
A representative of the Environmental Protection Agency (EPA) wants to select samples from 10 landfills. The director has 15 landfills from which she can collect samples. How many different samples
A pollster randomly selected 4 of 10 available people. How many different groups of 4 are possible?
Refer to the following table.a. Determine P(A1).b. Determine P(B1 | A2).c. Determine P(B2 and A3). Flrst Event Second Event A, A, 3 Total A, B, 2 B2 Total 3 4 10 3
All Seasons Plumbing has two service trucks that frequently need repair. If the probability the first truck is available is .75, the probability the second truck is available is .50, and the
Suppose P(X1) = .75 and P(Y2 | X1) = .40. What is the joint probability of X1 and Y2?
Suppose P(A) = .40 and P(B | A) = .30. What is the joint probability of A and B?
Suppose the two events A and B are mutually exclusive. What is the probability of their joint occurrence?
Let P(X) = .55 and P(Y) = .35. Assume the probability that they both occur is .20. What is the probability of either X or Y occurring?
The Tennessee Tourism Institute (TTI) plans to sample information center visitors entering the state to learn the fraction of visitors who plan to camp in the state. Current estimates are that 35% of
A sample of 352 subscribers to Wired magazine shows the mean time spent using the Internet is 13.4 hours per week, with a sample standard deviation of 6.8 hours. Find the 95% confidence interval for
A study conducted several years ago reported that 21 percent of public accountants changed companies within 3 years. The American Institute of CPA’s would like to update the study. They would like
As part of an annual review of its accounts, a discount brokerage selected a random sample of 36 customers and reviewed the value of their accounts. The mean was $32,000 with a sample standard
Refer to the Baseball 2016 data, which report information on the 30 Major League Baseball teams for the 2016 season. Assume the 2016 data represents a sample.a. Develop a 95% confidence interval for
Refer to the North Valley Real Estate data, which reports information on homes sold in the area during the last year. Select a random sample of twenty homes.a. Suppose that North Valley Real Estate
Slate is a daily magazine on the Web. Its business activities can be described by a number of variables. What is the level of measurement for each of the following variables?a. The number of hits on
Explain the difference between qualitative and quantitative variables. Give an example of qualitative and quantitative variables.
Explain the difference between a sample and a population.
Explain the difference between a discrete and a continuous variable. Give an example of each not included in the text.
Best Buy sells Fitbit wearable technology products that track a person’s activity. For example, the Fitbit technology collects daily information on a person’s number of steps so that a person can
The Struthers Wells Corporation employs more than 10,000 white-collar workers in its sales offices and manufacturing facilities in the United States, Europe, and Asia. A sample of 300 U.S. workers
The Wall Street Journal€™s website, www.wsj.com, reported the number of cars and light-duty trucks sold through October of 2014 and October of 2015. The top sixteen manufacturers are listed
The following chart depicts the earnings in billions of dollars for ExxonMobil for the period 2003 until 2014. Write a brief report discussing the earnings at ExxonMobil during the period. Was one
Refer to the North Valley Real Estate data, which report information on homes sold in the area last year. Consider the following variables: selling price, number of bedrooms, township, and mortgage
Refer to the Baseball 2016 data, which report information on the 30 Major League Baseball teams for the 2016 season. Consider the following variables: number of wins, payroll, season attendance,
Refer to the Lincolnville School District bus data, which report information on the school district’s bus fleet.a. Which of the variables are qualitative and which are quantitative?b. Determine the
In a marketing study, 100 consumers were asked to select the best digital music player from the iPod, the iRiver, and the Magic Star MP3. To summarize the consumer responses with a frequency table,
A set of data consists of 230 observations between $235 and $567. What class interval would you recommend?
The manager of the BiLo Supermarket in Mt. Pleasant, Rhode Island, gathered the following information on the number of times a customer visits the store during a month. The responses of 51 customers
The following frequency distribution reports the number of frequent flier miles, reportedin thousands, for employees of Brumley Statistical Consulting Inc. during the most recent quarter.Lead Time
Describe the similarities and differences of qualitative and quantitative variables. Be sure to include the following:a. What level of measurement is required for each variable type?b. Can both types
Describe the similarities and differences between a frequency table and a frequency distribution. Be sure to include which requires qualitative data and which requires quantitative data.
Speedy Swift is a package delivery service that serves the greater Atlanta, Georgia, metropolitan area. To maintain customer loyalty, one of Speedy Swiftâ€™s performance objectives is on-time
A data set consists of 145 observations that range from 56 to 490. What size class interval would you recommend?
In 2014, the United States exported a total of $376 billion worth of products to Canada. The five largest categories were:a. Use a software package to develop a bar chart.b. What percentage of the
In 2000, there were 720,000 cell phone subscribers worldwide. By 2015, the number of cell phone subscribers increased to 752,000,000. What is the geometric mean annual increase for the period?
Refer to the Baseball 2016 data that report information on the 30 Major League Baseball teams for the 2016 season. Create a frequency distribution for the Team Salary variable and answer the
JetBlue Airways is an American low-cost airline headquartered in New York City. Its main base is John F. Kennedy International Airport. JetBlue’s revenue in 2002 was $635.2 million. By 2014,
Compute the mean of the following population values: 6, 3, 5, 7, 6.
Compute the mean of the following population values: 7, 5, 7, 3, 7, 4.
a. Compute the mean of the following sample values: 5, 9, 4, 10.b. Show that Σ(x – x̅) = 0.
a. Compute the mean of the following sample values: 1.3, 7.0, 3.6, 4.1, 5.0.b. Show that Σ(x̅ − x) = 0.
Compute the mean of the following sample values: 16.25, 12.91, 14.58.
Suppose you go to the grocery store and spend $61.85 for the purchase of 14 items. What is the mean price per item?
There are 10 salespeople employed by Midtown Ford. The number of new cars sold last month by the respective salespeople were: 15, 23, 4, 19, 18, 10, 10, 8, 28, 19.(a) compute the arithmetic mean(b)
A mail-order company counted the number of incoming calls per day to the company’s toll free number during the first 7 days in May: 14, 24, 19, 31, 36, 26, 17.(a) compute the arithmetic mean(b)
The Cambridge Power and Light Company selected a random sample of 20 residential customers. Following are the amounts, to the nearest dollar, the customers were charged for electrical service last
A Human Resources manager at Metal Technologies studied the overtime hours of welders. A sample of 15 welders showed the following number of overtime hours worked last month.(a) compute the
AAA Heating and Air Conditioning completed 30 jobs last month with a mean revenue of $5,430 per job. The president wants to know the total revenue for the month. Based on the limited information, can
What would you report as the modal value for a set of observations if there were a total of:a. 10 observations and no two values were the same?b. 6 observations and they were all the same?c. 6
The following are the ages of the 10 people in the Java Coffee Shop at the Southwyck Shopping Mall at 10 a.m.(a) mean(b) median(c) mode. 21 41 21 23 24 23 29 20 33 37 42
Several indicators of long-term economic growth in the United States and their annual percent change are listed below.a. What is the median percent change?b. What is the modal percent change?
Sally Reynolds sells real estate along the coastal area of Northern California. Below are her total annual commissions between 2005 and 2015. Find the mean, median, and mode of the commissions she
The accounting firm of Rowatti and Koppel specializes in income tax returns for self-employed professionals, such as physicians, dentists, architects, and lawyers. The firm employs 11 accountants who
The demand for the video games provided by Mid-Tech Video Games Inc. has exploded in the last several years. Hence, the owner needs to hire several new technical people to keep up with the demand.
The Bookstall Inc. is a specialty bookstore concentrating on used books sold viathe Internet. Paperbacks are $1.00 each, and hardcover books are $3.50. Of the 50 books sold last Tuesday
The Loris Healthcare System employs 200 persons on the nursing staff. Fifty are nurse’s aides, 50 are practical nurses, and 100 are registered nurses. Nurse’s aides receive $8 an hour, practical
Andrews and Associates specialize in corporate law. They charge $100 an hour for researching a case, $75 an hour for consultations, and $200 an hour for writing a brief. Last week one of the

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