hw4sol - Solutions to Homework 4 Problem 3.17 a. The mean...

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Solutions to Homework 4 Problem 3.17 a. The mean price for models with a DVD player is 450 + 300 + 400 + 500 + 400 5 = 410 . The mean price for models without a DVD player is 300 + 300 + 360 + 290 + 300 5 = 310 . So it is about \$100 additional to perchase a unit with a DVD player. b. For models with a DVD player, the range is 500 - 300 = 200, the variance is ( x i - ¯ x ) 2 n - 1 = (450 - 410) 2 + ··· + (400 - 410) 2 4 = 5500 . The standard deviation is 5500 = 74 . 2. For models without a DVD player, the range is 360 - 290 = 70, the variance is ( x i - ¯ x ) 2 n - 1 = (300 - 310) 2 + ··· + (300 - 310) 2 4 = 800 . The standard deviation is 800 = 29 . 3. The prices for the models with a DVD player have a lot more variability that the prices for models without DVD players. Problem 3.19 a. The range of the data is 60 - 28 = 32. The quartiles for the data are Q 1 = 45 and Q 3 = 55. So the interquartile range is Q 3 - Q 1 = 55 - 45 = 10. b. First, the mean of the data is 48.3. The sample variance then is

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hw4sol - Solutions to Homework 4 Problem 3.17 a. The mean...

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