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Unformatted text preview: & & 2.25 a. 786 . 7 7 5 . 54 1 = = = & = n x x n i i b. The ranked observations are: 7.4, 7.5, 7.7, 7.8, 7.9, 8.0, 8.2. Since the sample size n = 7 is odd, the median is the (n+1)/2 = 4 th ranked observation, or median = 7.8 c. The consumer would more likely be interested in the company with the highest or maximum satisfaction rating. & 2.28 The Wall Street Journal is probably referring to the average number of cubes used per glass measured for some population that they have chosen. & 2.30 a. 1 . 9 10 91 1 = = = & = n x x n i i b. To find the median, the observations are ranked from smallest to largest: 5, 6, 8, 9, 9, 10 , 10, 10 , 11, 13 Since n = 10 is even, the median is the average of the n / 2 = 5 th and (n / 2) + 1 = 6 th ranked observations, or median = (9+10) / 2 = 9.5 c. Since the mean and the median are almost the same, the data is nearly symmetric. Therefore, either the mean or the median provides a good measure of the center of the distribution. & 2.34 a. 2 6 12 1 = = = & = n x x n i i b. The following table will be helpful in calculating the standard deviation s : i x x x i ( ) 2 x x i 2 0 0 4 2 4 0 2 4 3 1 1 1 1 1 Total 0 10 Then, ( ) 581 . 1 5 . 2 5 . 2 4 10 1 1 2 2 = = & = = = = s n x x s n i i or, using the computational formula, we have: 581 . 1 5 . 2 5 . 2 4 5 100 30 1 2 1 1 2 2 = = & = =  = = = s n n x x s n i i n i i & 2.57 Using the definition of percentiles given in the text, we can conclude that: $20,000 is the 60 th percentile, $30,000 is the 78 th percentile, and $40,000 is the 87 th percentile & 2.61 2....
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 Spring '08
 EduardoMontoya

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