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STAT 1124 Assignment 8 Model Answers

# STAT 1124 Assignment 8 Model Answers - or 0.7586 ± 0.0795...

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STAT 1124 – Section 2 Assignment 8 No Due Date Model Answers 1. Question 20.16 Page 506 H 0 : p = 0.5 H a : p > 0.5 Set α = 0.05 phat = 22/32 = 0.6875 Test statistic = z = (0.6875-0.5)/sqrt(0.5*(1-0.5)/32) = 2.12 p-value = P(z > 2.12) = 0.0170 Since the p-value is less than 0.05, we reject H 0. We have sufficient evidence that the candidate with the better face wins more than half of the time. 2. Question 20.28, Page 508 phat =19/172 = 0.1105 A 95% confidence interval is 0.1105 ± 1.96*sqrt(0.1105*(1-0.1105)/172) , or 0.1105 ± 0.04685 3. Question 20.30 (b), Page 509 Proportion preferring Times New Roman: phat =19/29 = 0.6552 A 95% confidence interval is 0.6552 ± 1.96*sqrt(0.6552*(1-0.6552)/29) , or 0.6552 ±0 .0173 Proportion preferring Gigi: phat =22/29 = 0.7586 A 95% confidence interval is 0.7586 ± 1.96*sqrt(0.7586*(1-0.7586)/29) ,

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Unformatted text preview: or 0.7586 ± 0.0795 4. Question 20.42, Page 511 What proportion of BMJ authors would agree that the journal should continue its system? phat =72/104 = 0.6923 A 95% confidence interval is 0.6923 ± 1.96*sqrt(0.6923*(1-0.6923)/104) , or 0.6923 ± 0.04526 Does the data give good evidence that more than two thirds (67%) of authors support continuing this system? H : p = 0.67 H a : p > 0.67 Set α = 0.05 Test statistic = z = (0.6923-0.67)/sqrt(0.67*(1-0.67)/104) = 0.55 p-value = P(z > 0.55) = 0.2912 Since the p-value is greater than 0.05, we do not reject H 0. We have insufficient evidence to conclude that more than two thirds (67%) of authors support continuing this system?...
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