The exchange rate of the Canadian dollar to one U.S. dollar was recorded monthly for the period 1971 to 2016. Draw a graph of these figures and interpret your findings.
> A manufacturing firm produces its products in batches using sophisticated machines and equipment. The general manager wanted to investigate the relationship between direct labor costs and the number of units produced per batch. He recorded the data from
> One way of measuring the extent of unemployment is through the help wanted index, which measures the number of want ads in the nation’s newspapers. The higher the index, the greater is the demand for workers. Another measure is the unemployment rate amon
> When the price of crude oil increases, do oil companies drill more oil wells? To determine the strength and nature of the relationship, an economist recorded the price of a barrel of domestic crude oil (West Texas crude) and the number of exploratory oil
> A real estate developer of single-family dwellings across the country is in the process of developing plans for the next several years. An analyst for the company believes that interest rates are likely to increase but remain at low levels. To to build,
> A regular feature in a newspaper asks readers to respond via e-mail to a survey that requires a yes or no response. In the following day’s newspaper, the percentage of yes and no responses are reported.Discuss why we should ignore these statistics.
> All Canadians have government-funded health insurance, which pays for any medical care they require. However, when traveling out of the country, Canadians usually acquire supplementary health insurance to cover the difference between the costs incurred f
> The unemployment rate is an important measure of a country’s economic health. The unemployment rate measures the percentage of people who are looking for work and who are without jobs. Unfortunately, it can be a misleading statistic bec
> Students who apply to MBA programs must take the Graduate Management Admission Test (GMAT). University admissions committees use the GMAT score as one of the critical indicators of how well a student is likely to perform in the MBA program. However, the
> Are the marks one receives in a course related to the amount of time spent studying the subject? To investigate this mysterious possibility, a student took a random sample of 10 students who had enrolled in an accounting class last semester. He asked eac
> A retailer wanted to estimate the monthly fixed and variable selling expenses. As a first step, she collected data from the past 8 months. The total selling expenses ($1,000) and the total sales ($1,000) were recorded and are listed below. Total Sales
> Refer to Exercise 7.30. Suppose that, on average, customers spend 10 minutes in each store they enter. Find the mean and standard deviation of the total amount of time customers spend in stores. Data from Exercise 7.30: A shopping mall estimates the prob
> Refer to Exercise 4.83. You’ve now learned that the two sample standard deviations are 16 and 12. a. Calculate the coefficient of correlation. What does this statistic tell you about the relationship between the two variables? b. Calculate the coefficie
> The covariance of two variables has been calculated to be −150. What does the statistic tell you about the two variables?
> To determine premiums for automobile insurance, companies must have an understanding of the variables that affect whether a driver will have an accident. The age of the driver may top the list of variables. The following table lists the number of drivers
> For each of the following examples of data, determine the type. a. The number of miles joggers run per week b. The starting salaries of graduates of MBA programs c. The months in which a firm’s employees choose to take their vacations d. The final letter
> The production of steel has often been used as a measure of the economic strength of a country. The next table lists the steel produced in the 20 largest steel-producing nations in 2014. The units are millions of metric tons. Use a graphical technique to
> a. What is meant by self-selected sample? b. Give an example of a recent poll that involved a self-selected sample. c. Why are self-selected samples not desirable?
> The planet may be threatened by global warming/climate change, possibly caused by burning fossil fuels (petroleum, natural gas, and coal) that produced carbon dioxide (CO2). The following table lists the top 15 producers of CO2 and the annual amounts (in
> The table below lists the electricity consumption (in Kilowatt-hours) in the top 20 electricity using countries. Graph the numbers to help describe the figures. Country Electricity Consumption (Kilowatt-Hours) Australia
> There are 42 gallons in a barrel of oil. The number of products produced and the proportion of the total are listed in the following table. Draw a graph to depict these numbers. Product Proportion Gasoline
> A random sample of households was selected. Each was asked how much they spent in food away from home (restaurants, fast food, etc.) last year. Calculate the quartiles and describe what information you’ve extracted from them.
> A shopping mall estimates the probability distribution of the number of stores mall customers actually enter, as shown in the table. Find the mean and standard deviation of the number of stores entered. 1 2 3 4 5 6 P(x) .04 .19 .22 28 .12 .09 .06
> In the United States, taxpayers are allowed to deduct mortgage interest from their incomes before calculating the amount of income tax they are required to pay. The Internal Revenue Service sampled 500 tax returns that had a mortgage interest deduction a
> For many restaurants, the amount of time customers linger over coffee and dessert negatively affects profits. To learn more about this variable, a sample of 200 restaurant groups was observed, and the amount of time customers spent in the restaurant was
> Do golfers who are members of private courses play faster than players on a public course? The amount of time taken for a sample of privatecourse and public-course golfers was recorded. Find the quartiles for each group and describe what you have learned
> A random sample of Boston Marathon runners was drawn and the times to complete the race were recorded. Determine the quartiles and briefly describe what they tell you.
> The career-counseling center at a university wanted to learn more about the starting salaries of the university’s graduates. They asked each graduate to report the highest salary offer received. The survey also asked each graduate to report the degree an
> The Travel Industry Association of America sponsored a poll that asked a random sample of people how much they spent in preparation for pleasure travel. Determine the quartiles and describe what they tell you.
> a. Describe why the Literary Digest poll of 1936 has become infamous. b. What caused this poll to be so wrong?
> How much do pets cost? A random sample of dog and cat owners was asked to compute the amounts of money spent on their pets (exclusive of pet food). Determine the quartiles and describe your findings.
> Accountemps, a company that supplies temporary workers, sponsored a survey of 100 executives. Each was asked to report the number of minutes they spend screening each job resume they receive. a. Compute the quartiles. b. What information did you derive f
> Many automotive experts believe that speed limits on highways are too low. One particular expert has stated that he thinks that most drivers drive at speeds that they consider safe. He suggested that the “correct” speed limit should be set at the 85th pe
> The natural remedy Echinacea is reputed to boost the immune system, which will reduce the number of flu and colds. A 6-month study was undertaken to determine whether the remedy works. From this study, the following probability distribution of the number
> Find the interquartile range of the following sample. 9 28 15 21 12 22 29 20 23 31 11 19 24 16 13
> Compute the interquartile range from the following data. 5 8 14 6 21 11 9 10 18 2
> Refer to Exercise 4.62. Determine the interquartile range. Data from Exercise 4.62: Calculate the 3rd and 6th deciles of the accompanying data. 7 18 12 17 29 18 4 27 30 2 4 10 21 5 8
> Refer to Exercise 4.61. Determine the interquartile range. Data from Exercise 4.61: Determine the first, second, and third quartiles of the following data. 10.5 14.7 15.3 17.7 15.9 12.2 10.0 14.1 13.9 18.5 13.9 15.1 14.7
> Calculate the 3rd and 6th deciles of the accompanying data. 7 18 12 17 29 18 4 27 30 2 4 10 21 5 8
> Determine the first, second, and third quartiles of the following data. 10.5 14.7 15.3 17.7 15.9 12.2 10.0 14.1 13.9 18.5 13.9 15.1 14.7
> Find the first and second quintiles (20th and 40th percentiles) of the data shown here. 52 61 88 43 64 71 39 73 51 60
> For each of the following sampling plans, indicate why the target population and the sampled population are not the same. a. To determine the opinions and attitudes of customers who regularly shop at a particular mall, a surveyor stands outside a large d
> Find the third and eighth deciles (30th and 80th percentiles) of the following data set. 26 23 29 31 24 22 15 31 30 20
> Calculate the first, second, and third quartiles of the following sample. 5 8 2 9 5 3 7 4 2 7 4 10 4 3 5
> After analyzing the frequency with which cross-country skiers participate in their sport, a sportswriter created the following probability distribution for X = number of times per year cross-country skiers ski. Find the following. a. P(3) b. P(X â
> Determine the first, second, and third quartiles of the data shown next. 2 4 6 8 10 12 14 16 18 20
> Black Friday in the United States is the day after Thanksgiving. Many retailers offer doorcrasher specials to induce customers to shop at their stores. The number of door-crasher specials is limited. However, the sale price is so low that people who want
> Refer to Exercise 3.54. Use the U.S. CPI monthly file to measure the Dow Jones Industrial Average in 1982–1984 constant dollars. What have you learned? Data from Exercise 3.54: The Jones Industrial Average was recorded monthly (close) from 1950 to 2016.
> The Jones Industrial Average was recorded monthly (close) from 1950 to 2016. Use a graph to describe these numbers.
> The exchange rate of the Japanese Yen to one U.S. dollar was recorded monthly for the period 1971 to 2016. Draw a graph of these figures and interpret your findings.
> The monthly value of U.S. exports to China (in $millions) and imports from China from 1985 to 2016 was recorded. a. Draw a line chart of U.S. exports to China. b. Draw a line chart of U.S. imports from China. c. Calculate the trade balance and draw a lin
> The monthly value of U.S. exports to Japan (in $millions) and imports from Japan from 1985 to 2016 was recorded. a. Draw a line chart of U.S. exports to Japan. b. Draw a line chart of U.S. imports from Japan. c. Calculate the trade balance and draw a lin
> List five important points to consider when designing a questionnaire.
> The monthly value of U.S. exports to Canada (in $millions) and imports from Canada from 1985 to 2016 was recorded. a. Draw a line chart of U.S. exports to Canada. b. Draw a line chart of U.S. imports from Canada. c. Calculate the trade balance and draw a
> A university librarian produced the following probability distribution of the number of times a student walks into the library over the period of a semester. Find the following probabilities. a. P(X ≥ 20) b. P(X = 60) c. P(X > 50) d.
> A sample of households was asked to report the amount of money they spend annually for fruits and vegetables. Compute the mean and standard deviation of these data. What do these statistics tell you about the distribution of the amounts?
> A random sample of homeowners was asked to report the amount of money they paid in property taxes last year. Compute the mean and standard deviation. Assuming that the amounts are highly positively skewed describe what the two statistics tell you.
> An amateur golf kept track of the scores of her last 100 rounds. Calculate the mean and standard deviation. Assuming that the distribution of scores is extremely skewed interpret the mean and standard deviation.
> Flight delays in airplane travel is a fact of life for travelers. Suppose that the time for each of a sample of 125 delays in arriving (in minutes) was recorded. Early arrivals are shown as negative numbers and on-time arrivals are represented by zeroes.
> Everyone is familiar with waiting lines or queues. For example, people wait in line at a supermarket to go through the checkout counter. There are two factors that determine how long the queue becomes. One is the speed of service. The other is the number
> To learn more about the size of withdrawals at a banking machine, the proprietor took a sample of 75 withdrawals and recorded the amounts. Determine the mean and standard deviation of these data, and describe what these two statistics tell you about the
> Variance is often used to measure the quality in production-line products. Suppose that a sample of steel rods that are supposed to be exactly 100 cm long is taken. The length of each is determined, and the results are recorded. Calculate the variance an
> Three men are trying to make the football team as punters. The coach had each of them punt the ball 50 times, and the distances were recorded. a. Compute the variance and standard deviation for each punter. b. What do these statistics tell you about the
> Many traffic experts argue that the most important factor in accidents is not the average speed of cars but the amount of variation. Suppose that the speeds of a sample of 200 cars were taken over a stretch of highway that has seen numerous accidents. Co
> a. List three methods of conducting a survey of people. b. Give an important advantage and disadvantage of each of the methods listed in part (a).
> A survey of Amazon.com shoppers reveals the following probability distribution of the number of books purchased per hit. a. What is the probability that an Amazon.com visitor will buy four books? b. What is the probability that an Amazon.com visitor wil
> There has been much media coverage of the high cost of medicinal drugs in the United States. One concern is the large variation from pharmacy to pharmacy. To investigate, a consumer advocacy group took a random sample of 100 pharmacies around the country
> A statistics practitioner determined that the mean and standard deviation of a data set were 120 and 30, respectively. What can you say about the proportions of observations that lie between each of the following intervals? a. 90 and 150 b. 60 and 180 c.
> A set of data whose histogram is extremely skewed yields a mean and standard deviation of 70 and 12, respectively. What is the minimum proportion of observations that a. are between 46 and 94? b. are between 34 and 106?
> Refer to Exercise 4.35. Approximately what proportion of observations a. are less than 46? b. are less than 58? c. are greater than 54? Data from Exercise 4.35: A set of data whose histogram is bell shaped yields a mean and standard deviation of 50 and 4
> A set of data whose histogram is bell shaped yields a mean and standard deviation of 50 and 4, respectively. Approximately what proportion of observations a. are between 46 and 54? b. are between 42 and 58? c. are between 38 and 62?
> Create a sample of five observations whose mean is 6 and whose standard deviation is 0.
> A friend calculates a variance and reports that it is –25.0. How do you know that he has made a calculation error?
> Refer to Exercise 4.31. Calculate the variance for each part. Was your answer in Exercise 4.31 correct? Data from Exercise 4.31: a. 17 b. 22 29 12 16 11 18 23 20 17 C. 24 37 6. 39 29
> Examine the three samples listed here. Without performing any calculations, indicate which sample has the largest amount of variation and which sample has the smallest amount of variation. Explain how you produced your answer. a. 17 b. 22 29 12 16 11
> Find the variance and standard deviation of the following sample. 0 −5 −3 6 4 −4 1 −5 0 3
> Refer to Exercise 7.22. a. Determine the probability distribution of the amount of money the arcade takes in per child. b. Use the probability distribution to calculate the mean and variance of the amount of money the arcade takes in. c. Compare the answ
> a. Briefly describe how you might design a study to investigate the relationship between smoking and lung cancer. b. Is your study in part (a) observational or experimental? Explain why.
> Determine the variance and standard deviation of the following sample. 12 6 22 21 23 13 15 17 21
> Calculate the variance of the following sample. 4 5 3 6 5 6 5 6
> Calculate the variance of the following sample. 9 3 7 4 1 7 5 4
> How much television were American adults watching in 2014 (TVHOURS)? Produce a histogram to help answer the question.
> How well were Americans doing financially in 2014. Draw a histogram of respondents’ incomes (RINCOME). Describe the shape.
> How educated were American adults in 2014? Draw a histogram to help provide a graphical answer (EDUC).
> Draw a histogram of the ages (AGE) of the respondents. What information do you draw from the histogram?
> The number of books shipped out daily by Amazon.com was recorded for 100 days. Draw a histogram and describe your findings.
> The volume of water used by each of a sample of 350 households was measured (in gallons) and recorded. Use a suitable graphical statistical method to summarize the data. What does the graph tell you?
> Refer to Exercise 7.23. Suppose that each game costs the player 25 cents. Use the laws of expected value and variance to determine the expected value and variance of the amount of money the arcade takes in. Data from Exercise 7.23: Determine the mean and
> Each of a sample of 240 tomatoes grown with a new type of fertilizer was weighed (in ounces) and recorded. Draw a histogram and describe your findings.
> A soft drink manufacturer has been supplying its cola drink in bottles to grocery stores and in cans to small convenience stores. The company is analyzing sales of this cola drink to determine which type of packaging is preferred by consumers. a. Is this
> Is it possible for a sample to yield better results than a census? Explain.
> Briefly describe three types of nonsampling error.
> a. Explain the difference between sampling error and nonsampling error. b. Which type of error in part (a) is more serious? Why?
> A statistics practitioner wants to estimate the mean age of children in his city. Unfortunately, he does not have a complete list of households. Describe a sampling plan that would be suitable for his purposes.
> The operations manager of a large plant with four departments wants to estimate the person-hours lost per month from accidents. Describe a sampling plan that would be suitable for estimating the plantwide loss and for comparing departments.
> A telemarketing firm has recorded the households that have purchased one or more of the company’s products. These number in the millions. The firm would like to conduct a survey of purchasers to acquire information about their attitude concerning the tim
> A large university campus has 60,000 students. The president of the students’ association wants to conduct a survey of the students to determine their views on an increase in the student activity fee. She would like to acquire information about all the s
> Monthly returns for the Toronto Stock Exchange Index and the following selected stocks on the Toronto Stock Exchange were recorded for the years 2011 to 2015: Rogers Communication (RCI.B) and Telus (T) Calculate the beta coefficient and the coefficient o
> Refer to Exercise 7.22. Determine the mean and variance of the number of games played. Data from Exercise 7.22: After watching a number of children playing games at a video arcade, a statistics practitioner estimated the following probability distributio
> Monthly returns for the Toronto Stock Exchange Index and the following selected stocks on the Toronto Stock Exchange were recorded for the years 2011 to 2015: Encana (ECA), Enbridge (ENB), and Suncor Energy (SU) Calculate the beta coefficient and the coe
> Monthly returns for the Toronto Stock Exchange Index and the following selected stocks on the Toronto Stock Exchange were recorded for the years 2011 to 2015: Bank of Montreal (BMO), Bank of Nova Scotia (BNS), and Royal Bank of Canada (RY) Calculate the
