sol.hw6.stat3011

# sol.hw6.stat3011 - Homework 6 Solutions Yicheng Kang 6.30 x...

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Homework 6 Solutions Yicheng Kang October 29, 2010 6.30 z = x - μ σ = - . 75 which corresponds to a cumulative probability of 0 . 2266. z = x - μ σ = . 5 which corresponds to a cumulative probability of 0 . 6915. 0 . 6915 - 0 . 2266 = 0 . 4649(rounds to 0 . 46), the approximate proportion of students who get a C. 6.61 z = (258 - 281 . 9) / 11 . 4 = - 2 . 10; according to Table A, 0 . 0179 fall below this z-score; thus, propor- tion 0 . 018 of babies would be classiﬁed as premature. 7.20 a) The mean would be 8 . 20. Standard error = σ/ n = 3 / 100 = 0 . 30. b) z = (8 , 95 - 8 . 20) / 0 . 3 = 2 . 5.Table A tells us that 0 . 994 is the proportion below this z-score. Thus, the probability that the restaurant makes a proﬁt that day is 0 . 994. 7.24 a)The center of the population distribution is the mean of the population of 60. The spread is the standard deviation of the population,16. 1

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b)The center of the data distribution 58 . 3 The spread is the standard deviation of 15 . 0. It is probably skewed to the left. c) The center of the sampling distribution mean is 60. The spread, or standard error, is
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sol.hw6.stat3011 - Homework 6 Solutions Yicheng Kang 6.30 x...

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