quiz1.pdf - STAT 200 QUIZ 1 Solutions Section 6380 Fall...

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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 book Location 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 Q 1 : Find the location L of the 25 th percentile in the sorted list: 25 1 12 .12 3 100 100 4 k L n = = = Because L = 3 is a whole number, the 25 th percentile (first quartile) is located between 3 rd and 4 th checkout time in the sorted list. The 3 rd and 4 th checkout times are found to be 6.1 and 6.7, so the first quartile Q 1 is (6.1 + 6.7) / 2 = 6.4 minutes
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