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STAT 200 QUIZ 1 Solutions Section 6380 Fall 2013 •The quiz covers Chapters 1, 2 and 3. (For Questions 1 to 6) The checkout times (in minutes) for 12 randomly selected customers at a large supermarket during the store’s busiest time are as follows: 4.6 8.5 6.1 7.8 10.7 9.3 12.4 5.8 9.7 8.8 6.7 13.2 1. (2 points) (Show work)What is the mean checkout times based on the 12 checkout times. The mean checkout time based on the raw data = (4.6 + 8.5 + 6.1 + 7.8 + 10.7+ 9.3 + 12.4 + 5.8 + 9.7 + 8.8 + 6.7 + 13.2) / 12 = 103.6 / 12 = 8.63 2. (6 points) (Show work)Give a 5-number summary of the checkout time, and construct the corresponding boxplot. Arrange the checkout times from low to high: Method 1 : Use the approach from the bookLocation 1 2 3 4 5 6 7 8 9 10 11 12 Data 4.6 5.8 6.1 6.7 7.8 8.5 8.8 9.3 9.7 10.7 12.4 13.2 Minimum: 4.6 Q1: Find the location L of the 25thpercentile in the sorted list: 25112.1231001004kLn=⋅=⋅=Because L = 3 is a whole number, the 25thpercentile (first quartile) is located between 3rdand 4thcheckout time in the sorted list. The 3rdand 4thcheckout times are found to be 6.1 and 6.7, so the first quartile Q1is (6.1 + 6.7) / 2 = 6.4 minutes
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