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The Bureau of Labor Statistics? American Time Use...

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The Bureau of Labor Statistics? American Time Use Survey showed that the amount of time spent using a computer for leisure varied greatly by age. Individuals age 75 and over averaged .25 hour (15 minutes) per day using a computer for leisure. Individuals ages 15 to 19 spend .9 hour per day using a computer for leisure. If these times follow an exponential distribution, find the proportion of each group that spends: rev: 10_13_2011 1. value: 10 points (a) Less than 14 minutes per day using a computer for leisure. (Round your answers to 4 decimal places.) Proportion and rev: 10_13_2011 check my workeBook LinkView Hint #1 2. value: 10 points (b) More than two hours. (Round your answers to 4 decimal places.) Proportion and rev: 10_13_2011 check my workeBook LinkView Hint #1 3. value: 10 points (c) Between 28 minutes and 84 minutes using a computer for leisure. (Round your answers to 4 decimal places.) Proportion and rev: 10_13_2011 check my workeBook LinkView Hint #1 4. value: 10 points (d) Find the 25th percentile. Seventy five percent spend more than what amount of time? (Round your answers to 2 decimal places.) Amount of time for individuals age 75 and over minutes Amount of time for individuals ages 15 to 19 minutes rev: 10_13_2011 5. value: 10 points A study of long-distance phone calls made from the corporate offices of General Electric revealed the length of the calls, in minutes, follows the normal probability distribution. The mean length of time per call was 3.5 minutes and the standard deviation was 0.70 minutes. (a) What fraction of the calls last between 3.5 and 4 minutes? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.) Fraction of calls (b) What fraction of the calls last more than 4 minutes? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.) Fraction of calls (c) What fraction of the calls last between 4 and 5 minutes? (Round your answer to 4 decimal places.) Fraction of calls (d) What fraction of the calls last between 3 and 5 minutes? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.) Fraction of calls (e) As part of her report to the president, the director of communications would like to report the length of the longest (in duration) 3 percent of the calls. What is this time? (Round z-score computation to 2 decimal places and your final answer to 2 decimal places.) Duration 6. value: 10 points According to the South Dakota Department of Health, the mean number of hours of TV viewing per week is higher among adult women than men. A recent study showed women spent an average of 39 hours per week watching TV and men 33 hours per week. Assume that the distribution of hours watched follows the normal distribution for both groups, and that the standard deviation among the women is 4.7 hours and is 5.3 hours for the men. (a) What percent of the women watch TV less than 43 hours per week? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.) Probability (b) What percent of the men watch TV more than 30 hours per week? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.) Probability (c) How many hours of TV do the two percent of women who watch the most TV per week watch? Find the comparable value for the men. (Round your answers to 3 decimal places.) Number of hours Women Men 7. value: 10 points According to a government study among adults in the 25- to 34-year age group, the mean amount spent per year on reading and entertainment is $1,896. Assume that the distribution of the amounts spent follows the normal distribution with a standard deviation of $596. (Round z-score computation to 2 decimal places and your final answer to 2 decimal places. Omit the "%" sign in your response.) (a) What percent of the adults spend more than $2,350 per year on reading and entertainment? Percent % (b) What percent spend between $2,350 and $2,800 per year on reading and entertainment? Percent % (c) What percent spend less than $1,150 per year on reading and entertainment? Percent % 8. value: 10 points The net sales and the number of employees for aluminum fabricators with similar characteristics are organized into frequency distributions. Both are normally distributed. For the net sales, the mean is $180 million and the standard deviation is $25 million. For the number of employees, the mean is 1,500 and the standard deviation is 120. Clarion Fabricators had sales of $170 million and 1,850 employees. (a) Convert Clarion's sales and number of employees to z values. (Negative amount should be indicated by a minus sign. Round your answers to 2 decimal places.) z value Net sales Employees ________________________________________ (b) Interpret the z values obtained in Req 1. (Round your answers to 2 decimal places.) Net sales are standard deviations the mean. Employees is standard deviations the mean. (c) Compare Clarion's sales and number of employees with those of the other fabricators. (Round your answers to 2 decimal places. Omit the "%" sign in your response.) % of the aluminum fabricators have greater net sales compared with Clarion. Only % have more employees than Clarion. 9. value: 10 points The accounting department at Weston Materials Inc., a national manufacturer of unattached garages, reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times follow the normal distribution. (a-1) Determine the z values for 29 and 34 hours. (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.) 29 hours corresponds to Z 34 hours corresponds to Z ________________________________________ (a-2) What percent of the garages take between 32 hours and 34 hours to erect? (Round your answer to 2 decimal places. Omit the "%" sign in your response.) Percentage % (b) What percent of the garages take between 29 hours and 34 hours to erect? (Round your answer to 2 decimal places. Omit the "%" sign in your response.) Percentage % (c) What percent of the garages take 28.7 hours or less to erect? (Round your answer to 2 decimal places. Omit the "%" sign in your response.) Percentage % (d) What is the value that separates the 5% of the garages that take the longest to erect? (Round your answer to 1 decimal place.) Hours 10. value: 10 points Fast Service Truck Lines uses the Ford Super Duty F-750 exclusively. Management made a study of the maintenance costs and determined the number of miles traveled during the year followed the normal distribution. The mean of the distribution was 60,000 miles and the standard deviation 2,000 miles. (Round z-score computation to 2 decimal places and your final answer to 2 decimal places. Omit the "%" sign in your response.) (a) What percent of the Ford Super Duty F-750s logged 65,200 miles or more? Percent % (b) What percent of the trucks logged more than 57,060 but less than 58,280 miles? Percent % (c) What percent of the Fords traveled 62,000 miles or less during the year? Percent % 11. value: 10 points The Cincinnati Enquirer, in its Sunday business supplement, reported that the mean number of hours worked per week by those employed full time is 43.9. The article further indicated that about one-third of those employed full time work less than 40 hours per week. (a) Given this information and assuming that number of hours worked follows the normal distribution, what is the standard deviation of the number of hours worked? (Round z value to 2 decimal places and your final answers to 2 decimal places.) Standard deviation (b-1) The article also indicated that 20 percent of those working full time work more than 49 hours per week. Determine the standard deviation with this information. (Round z value to 2 decimal places and your final answers to 2 decimal places.) Standard deviation (b-2) Are the two estimates of the standard deviation similar? (b-3) What would you conclude?

 

Paper#11419 | Written in 18-Jul-2015

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