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HW 8 Solutions

# HW 8 Solutions - 1211 would be required STATW1211.005 Prof...

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STATW1211.005 Prof. Zhang TR 02:40P-03:55P Homework 8 – Solutions Textbook: Probability and statistics for engineering and the sciences (7 th edition) by Jay L. Devore Chapter 9: Question 49 Parameter of interest: p 1 – p 2 = true difference in proportions of those responding to two different survey covers. Let p 1 = Plain, p 2 = Picture. Reject H 0 if p-value < .10 ; p-value = .4247 Fail to Reject H 0 . The data does not indicate that plain cover surveys have a lower response rate. Question 51 a. Let p 1 and p 2 denote the true incidence rates of GI problems for the olestra and control groups, respectively. We wish to test H 0 : p 1 μ 2 = 0 v. H a : p 1 p 2 ≠ 0. The pooled proportion is = .1667, from which the relevant test statistic is z = = 0.78. The two-sided P-value is 2P(Z ≥ 0.78) = .433 > α = .05, hence we fail to reject the null hypothesis. The data do not suggest a statistically significant difference between the incidence rates of GI problems between the two groups. b. , so a common sample size of m = n =

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Unformatted text preview: 1211 would be required. STATW1211.005 Prof. Zhang TR 02:40P-03:55P Chapter 12: Question 11 a. expected change for a one degree increase = -.01, and is the expected change for a 10 degree increase. b. , and . c. The probability that the first observation is between 2.4 and 2.6 is . The probability that any particular one of the other four observations is between 2.4 and 2.6 is also .8164, so the probability that all five are between 2.4 and 2.6 is . d. Let Y 1 and Y 2 denote the times at the higher and lower temperatures, respectively. Then Y 1 - Y 2 has expected value . The standard deviation of Y 1 - Y 2 is . Thus . Question 19 N = 14, , , , , a. , , so we use the equation . b. c. Estimated expected change d. No, the value 500 is outside the range of x values for which observations were available (the danger of extrapolation). Question 23 a. Using the given y i ’s and the formula , . The computation formula gives b. so ....
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