SOLUTION: A researcher wants to estimate the mean blood cholesterol level of young men ages 15-25 with a 81.26% confidence interval. The blood cholesterol level of young men follows a Normal

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Question 1197914: A researcher wants to estimate the mean blood cholesterol level of young men ages 15-25 with a 81.26% confidence interval. The blood cholesterol level of young men follows a Normal distribution with standard deviation = 30 mg/dl. How large a sample would the researcher need to take to estimate the mean blood cholesterol to within 9 mg/dl?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
ME+=+z%2Asigma%2Fsqrt%28n%29
0r
n+=+%28z%2Asigma%2FME%29%5E2
81.26% confidence interval %28100-81.26%29%2F2= 9.7% z(.8126 + .097) = 1.34

n+=%2830%2A1.34%2F9%29%5E2 = 19.98 (always round Up )
n = 20