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Take a Test - Andrea Montgomery-Google Chrome Secure I https://www.matha.com/Student/PlayerTest.aspx?testId=167153937&centerwinyes; MAT135C01 Intro to Statistics: MA1 FA17 (Dale Blake) Test: Module 4 Test (Chapters 8, 9, 10, 11) Time Remaining: 02:5723 Submit Test This Question: 1 pt 60120( complete) h This Test: 20 pts possible oh A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many points with 99% confidence assuming s-172 based on earlier studies? confidence affect the sample size required? subjects are needed to estimate the mean HDL cholesterol within 2 A 99% confidence level requires subjects (Round up to the nearest subject ) A 95% confidence level requires [ ] subjects (Round up to the nearest subject ) How does the decrease in confidence affect the sample size required? 0 A. OB. O C. Decreasing the confidence level decreases the sample size needed Decreasing the confidence level increases the sample size needed The sample size is the same for all levels of confidence Click to select your answer(s)

Explanation / Answer

B) At 99% confidence interval the critical value is z0.005 = 2.58

Margin of error = 2

Or, z0.005 * sd/sqrt (n) = 2

Or, 2.58 * 17.2/sqrt (n) = 2

Or, sqrt(n) = 2.58 * 17.2/2

Or, sqrt (n) = 22.188

Or, n = 492

A 99% confidence level requires 492 subjects.

B) At 95% confidence interval the critical value is z0.025 = 1.96

Margin of error = 2

Or, z0.025 * sd/sqrt (n) = 2

Or, 1.96 * 17.2/sqrt (n) = 2

Or, sqrt(n) = 1.96 * 17.2/2

Or, sqrt (n) = 16.856

Or, n = 284

Option-A) Decreasing the confidence level decreases the sample size needed.

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