3-9. The manager for the Jiffy Lube in Saratoga, Florida, has collected data on the number of customers who agreed to purchase an air lter when they were also having their oil changed. The sample data are shown as follows: 21 19 21 19 19 20 18 12 20 19 17 14 21 22 25 21 22 23 10 19 25 14 17 18 , ,"j, "H ,. W, [aw ,, , 3-11. The Xang Corporation operates ve clothing suppliers in China to provide merchandise for Nike. Nike recently sought information from the ve plants. One variable for which data were collected was the total money (in U.S. dollars) the company spent on medical support for its employees in the rst three months of the year. Data on number of employees at the plants are also shown. These data are as follows: Medical $7,400 $14,400 $12,300 $6,200 $3,100 Employees 123 402 256 109 67 a. Compute the weighted mean medical payments for these ve plants using number of employees as the weights. b. Explain why Nike would desire that a weighted average be computed in this situation rather than a simple numeric average. 3-12. The Tru-Green Lawn Company provides yard care services for customers throughout the Denver area. The company owner recently tracked the time his eld employees spent at a sample of customer locations. He was hoping to use these data to help him with his scheduling and to establish billing rates. The following sample data, in minutes, were recorded: 31 27 29 22 24 30 28 21 29 26 22 17 17 20 38 10 38 25 27 23 23 13 17 34 25 29 22 22 14 1 1 29 26 29 29 37 32 27 26 18 22 Describe the central tendency of these data by computing the mean, median, and mode. Based on these measures, can you conclude that the distribution of time spent at customer locations is skewed or symmetric? 3-13. Eastern States Bank and Trust monitors its drive-thru service times electronically to ensure that its speed of service is meeting the company's goals. A sample of 28 drivethru times was recently taken and is shown here. CHAPTER 3 I Describing Data Using Numerical Measures 105 location and building amenities. Currently, all six buildings are fully leased at the prices shown here. Price per Number of Square Foot Square Feet Building 1 $ 75 125,000 Building2 $ 85 37,500 Building 3 $ 90 77,500 Building 4 $ 45 35,000 Building 5 $ 55 60,000 Building 6 $1 10 130,000 a. Compute the weighted average (mean) price per square foot for these buildings. b. Why is the weighted average price per square foot preferred to a simple average price per square foot in this case? 3-15. Business Week recently reported that L. G. Philips LCD Co. would complete a new factory in Paju, South Korea. It will be the world's largest maker of liquid crystal display panels. The arrival of the plant means that atpanel LCD televisions would become increasingly affordable. The average retail cost of a 20\" LCD television in 2000 was $5,139. To obtain what the average retail cost of a 37'" LCD was in 2008, a survey yielded the following data (in $U.S.): 606.70 558.12 625.82 533.70 464.37 511.15 400.56 538.20 531.64 632.14 474.86 567.46 588.39 528.78 610.32 564.71 912.68 475.87 545.25 589.15 a. Calculate the mean cost for these data. b. Examine the data presented. Choose an appropriate measure of the center of the data, justify the choice, and calculate the measure. c. The inuence an observation has on a statistic may