A quality control engineer at a pharmaceutical company is in

A quality control engineer at a pharmaceutical company is interested in

verifying the mean aspirin content in the company\'s aspirin tablets. Assuming aspirin content

follows a normal distribution with standard deviation of 5 mg, how large of a sample must

be taken in order for the margin of error to be within 1 mg with 99% confidence?

Solution

Compute Sample Size
n = (Z a/2 * S.D / ME ) ^2
Z/2 at 0.05% LOS is = 1.96 ( From Standard Normal Table )
Standard Deviation ( S.D) = 5
ME =1
n = ( 1.96*5/1) ^2
= (9.8/1 ) ^2
= 96.04 ~ 97