Review1 - Review # 1 Chapter 4 Chapter 6 Chapter 7 Chapter...

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1 Review # 1 Chapter 4 Chapter 6 Chapter 7 Chapter 8

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2 Problem 1 (Calculations) The ages of employees of a fast-food outlet are as follows: 19, 19, 65, 20, 21, 18, 20. a) Compute the mean, the median, and the mode of the ages Mean = (19+19+…+20)/7 = 26 Median = the center of the sorted series = 20 {18, 19, 19, 20, 20, 21, 65} Mode = the number with the largest frequency = 19, 20 Chapter 4: Descriptive Statistics Numerical Methods Mean = 19.5 Median = 19.5 = (19+20)/2 Mode = 19, 20 no change. The mean is sensitive to extreme value; the median and the mode are less sensitive. b) Assume the oldest employee retires
3 Problem 2 (Excel, interpretation) The summer income of a sample of 125 second-year business students are stored in Prob 2 Calculate the mean and the median What do the two measures of central location tell you about the income? Which measure should be used to summarize the data? Measures of Central location (Excel, interpretation)

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4 Ch. 4: Measures of Central location Problem 2 - solution The distribution is reasonably symmetrical, but a few low incomes have pulled the mean below the median, resulting in a distribution slightly skewed to the left. Either measure could be used, but the median is better because it is not affected by a few low incomes. Mean 2992.56 Standard Error 49.815744 Median 3016 Mode 2817 Standard Deviation 556.95695 Sample Variance 310201.04 Kurtosis 0.271249 Skew ness -0.3106334 Range 2958 Minimum 1333 Maximum 4291 Sum 374070 Count 125
5 Problem 2 - solution The distribution is reasonably symmetrical, but a few low incomes have pulled the mean below the median, resulting in a distribution slightly skewed to the left. Either measure could be used, but the median is better because it is not affected by a few low incomes. Frequency 0 10 20 30 40 50 1800 2300 2800 3300 3800 4300 More Measures of Central location

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6 Measures of Central location Problem 3 (Excel, interpretation) The owner of a hardware store that sells electrical wires by the meter is considering selling the wire in pre-cut lengths to save on labor cost. A sample of wire sold over the course of 1 week was recorded (Prob3.xls). A) Compute the mean, median and mode B) What is the weakness of each measure in providing useful info? C) How might the owner decide on the lengths to pre-cut?
7 A) The mean resides to the right of the median. The distribution of lengths is somewhat asymmetrical, skewed to the right (there must be some long wires sold that affect the mean value). Lengths Mean 6.17 Standard Error 0.3824575 Median 5 Mode 5 Standard Deviation 3.824575 Sample Variance 14.627374 Kurtosis 8.6410756 Skew ness 2.7809472 Range 22 Minimum 3 Maximum 25 Sum 617 Count 100 Sales 0 20 40 60 80 3 7 11 15 19 23 27 More Measures of Central location

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8 Measures of Central location B) The mean is unduly influenced by extreme observations. The median doesn’t indicate what lengths are most preferred. The mode doesn’t consider any desired lengths other than the one most frequently purchased.
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This note was uploaded on 11/11/2010 for the course ISDS 361A ISDS 361A taught by Professor Goldstein during the Fall '10 term at CSU Fullerton.

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Review1 - Review # 1 Chapter 4 Chapter 6 Chapter 7 Chapter...

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