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# 1. A RANDOM SAMPLE OF 200 FRESHMAN AND 100 SENIORS AT FERRIS HIGH

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Author: Christine Farr
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1. A random sample of 200 freshman and 100 seniors at Ferris High School are asked whether they agree with a plan to excuse upper class students (juniors and seniors) a half hour early while keeping underclass students (freshmen and sophomores) in school for the last half hour. Of the students sampled, 160 freshmen opposed the plan and 20 seniors opposed the plan.-Is there a difference (5% level of significance) between the proportion of freshmen who oppose the plan and the proportion of seniors who oppose it? Do a complete test showing all the parts.2) In a study of heart surgery, one issue was the effect of drugs called beta-blockers on the pulse rate of patients during surgery. The available subjects were divided at random into two groups of 30 subjects each. One group received the beta-blocker and the other received a placebo. The pulse rate of each patient at a critical point during the operation was recorded. The treatment group had a mean of 65.2 and standard deviation of 7.8. For the control group, the mean was 70.3 and standard deviation was 8.3. You want to see if the beta-blockers reduce the pulse rate. a. Test the data at the 5% level of significance. Give good statistical evidence. (ie., use the appropriate 4-part format). b. Give a 99% confidence interval for the difference in mean pulse rates. c. Interpret the confidence interval you constructed

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