Determine the sample size n to obtain 95 interval estimate o

Determine the sample size, n, to obtain 95% interval estimate of the true mean of the breast cancer tumor size, to be taken from an extremely large US database such that: the size n assures us that the estimate is within 0.1 cm of the population mean given the population variance ² = .81?

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) = Sqrt(0.81) = 0.9
ME = 0.1
n = ( 1.96*0.9/0.1) ^2
= (1.764/0.1 ) ^2
= 311.17 ~ 312