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Quiz #6-2

# Quiz #6-2 - Started on Monday 25 February 2008 09:46 PM...

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Started on: Monday, 25 February 2008, 09:46 PM Completed on: Monday, 25 February 2008, 10:42 PM Time taken: 56 mins 31 secs Raw score: 10/10 (100%) Grade: 10 out of a maximum of 10 (3280) 1 Marks: 1 The objective of a study is to find out whether meditation lowers stress level. Thirty six people volunteer to participate in the study. They meditated for one hour and their stress level was measured before and after meditaton. Given the following data what is your decision regarding the null (assume a two-tailed alternative hypothesis)? d = stress level after meditation minus stress level before meditation dbar or the mean of stress level after minus before meditation = 12 S(d) or standard deviation of the difference between stress level after and before mediation = 4 N = 36 Choose one answer. a. Reject the null and conclude that meditation lowers the stress level. b. Fail to reject the null and coclude that meditation does not lower the stress level. c. We can reject the null at 95% level of confidence, but, we cannot reject it at 99 level of confidence. d. We need the mean and the standard deviation for stress level before and after meditation to calculate t and decide about H0. Correct Marks for this submission: 1/1. (3278) 2 Marks: 1

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We showed that for the two sample test of the mean, you calculate t by dividing the difference in the sample means by S of (X bar 1 minus Xbar 2) What does (S of X bar 1 minus Xbar 2) show? Choose one answer. a. variance of sample one minus sample two. b. Standard deviation of the difference between X1 and X2 distribution c. standard deviation of the difference between two population means d. standard deviation of (Xbar 1 - Xbar 2) distribution Correct Marks for this submission: 1/1. (3282) 3 Marks: 1 A statistics professor wants to examine the effect of on line quizzes on students' ability to interpret confidence intervals. He randomly assigns his class of 25 students to two groups of 12 and 13. He gives both groups the same lecture on confidence interval. In addition he has one group take an on-line quiz about confidence intervals.
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Quiz #6-2 - Started on Monday 25 February 2008 09:46 PM...

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