STA 2023 Quiz 10 Answers - Quiz10Fall Quiz10Fall Part1of6...

Unformatted text preview: 5/4/2015 Quiz 10 Fall Quiz 10 Fall Part 1 of 6 ­ 1.0/ 1.0 Points 1.0/ 1.0 Points Question 1 of 6 A major grocery store chain is trying to cut down on waste. Currently, they get peaches from two different distributors, WholeFruits and GreenGrocer. Out of a two large shipments, the manager randomly selects items from both suppliers and counts the number of items that are not sell­able due to bruising, disease or other problems. She then makes a confidence interval. Is there a significant difference in the quality of the peaches between the two distributors? 95% CI for pW­pG:(­0.156, 0.064) A.We are 95% confident that the proportion of non sell­able peaches from Whole Fruits is anywhere between 6.4% and 15.6%. B.We are 95% confident that the proportion of non sell­able peaches for Whole Fruits is about ­6.4% and 15.6%. C.We are 95% confident that the proportion of non sell­able items for Whole Fruits is anywhere between 6.4% and 15.6% HIGHER than the proportion of non sell­able items for Green Grocer. D.We are 95% confident that the proportion of non sell­able items for Whole Fruits is anywhere between 6.4% and 15.6% LOWER than the proportion of non sell­able items for Green Grocer. E.We are 95% confident that the proportion of non sell­able items for Whole Fruits is anywhere between 15.6% LOWER and 6.4% HIGHER than the proportion of non sell­able items for Green Grocer. Part 2 of 6 ­ 1.0/ 1.0 Points 1.0/ 1.0 Points Question 2 of 6 Do students that are "Greek" (those who belong to a sorority/fraternity) have a tendency to be more involved in student government events than students who are "not Greek"? Specifically, do more "Greek" students then "not Greek" vote in the student elections? Let "Greek" students be group A and "Not­Greek" students be group B. Out of 250, 200 randomly selected "Greek" students voted in the last election. Out of 500, 140 randomly selected "not Greek" students voted in the last election. How would we write the alternative hypothesis? A.Ha: pA ­ pB = 0 B.Ha: pA ­ pB > 0 C.Ha: pA ­ pB < 0 D.Ha: pA ­ pB does not equal 0 Part 3 of 6 ­ 1.0/ 1.0 Points 1.0/ 1.0 Points Question 3 of 6 When we make inferences about the difference of two independent population proportions, what assumptions do we need to make? Mark all that apply. ­1d92­40b4­a137­7b83eeeed0ee/jsf/select/selectIndex 1/3 5/4/2015 Quiz 10 Fall A. Random samples. Feedback: We always need to do this. B. Normal distribution of the response variable. C. Sample size must be greater than or equal to 30. D. Counts of successes and failures at least 15 each for each group. Feedback: This is necessary for the distribution of p­hat to be fairly symmetric (not too extreme in either direction)­ only in the case of one proportion. E. The sum of the counts of successes and failures must be greater than 30. Part 4 of 6 ­ 1.0/ 1.0 Points 1.0/ 1.0 Points Question 4 of 6 A social scientist is interested in determining if there is a significant difference in the proportion of Republicans between two areas of town. He takes independent random samples of 20 families in each area of town and a significance test was conducted. The p­value was 0.016. What should be our conclusions? A.The evidence is pretty strong ­ there is a difference in the proportion of Republicans between the two areas of town. Feedback: correct ­ small p­value indicates significant differences, and a p­value of .016 is pretty small. B.The evidence is pretty strong ­ there is no significant difference in the proportion of Republicans between the two areas of town. C.We do not have enough evidence to say that there is a significant difference in the proportion of Republicans between the two areas of town. Part 5 of 6 ­ 1.0/ 1.0 Points Question 5 of 6 What is the definition of Type 2 error? 1.0/ 1.0 Points A.Rejecting the null hypothesis when the null hypothesis is really false. B.Failing to reject the null hypothesis when the null hypothesis is really false. C.Rejecting the null hypothesis when the null hypothesis is really true. D.Failing to reject the null hypothesis when the null hypothesis is really true. Feedback: Check the definition in your textbook or lab workbook. Part 6 of 6 ­ 1.0/ 1.0 Points 1.0/ 1.0 Points Question 6 of 6 In 2012, the General Social Survey included a question that asked respondents if they had "often/sometimes" ­1d92­40b4­a137­7b83eeeed0ee/jsf/select/selectIndex 2/3 5/4/2015 Quiz 10 Fall been treated rudely at work. Out of 614 men, 62 said yes they had "often/sometimes" been treated rudely at work. Out of 589 women, 79 said yes they had "often/sometimes" been treated rudely at work. What is the pooled proportion for the null hypothesis Ho:p1­p2=0 vs. alternative hypothesis Ha: p1­p2 does not equal 0? A.0.0739 B.0.101 C.0.134 D.0.117 E.Unknown ­1d92­40b4­a137­7b83eeeed0ee/jsf/select/selectIndex 3/3 ...
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