A taxi company tests a random sample of 10 steel-belted radial tires of a certain brand and recorded the following tread wear: 48,000, 53,000. 45,000. 61,000, 59,000, 56,000, 63,000, 49,000, 53,000, and 54,000 kilometers. Use the results of Exercise 8.14. To find the standard deviation of this set of data by first dividing each observation by 1000 and then subtracting 55