The sample size needed to estimate a population mean within 2 units with a 95% confidence when the population standard deviation equals 8 is
A) 9
B) 61
C) 62
D) 8
E) 50

Question

Quizplus · Accepted Answer

We use the formula for sample size calculation:
n = (zα/2 * σ / E) ^ 2
where zα/2 is the z-score for a 95% confidence level which is 1.96, σ is the population standard deviation which is given as 8, and E is the margin of error which is 2. Therefore,
n = (1.96 * 8 / 2) ^ 2 = 61.24, which rounds up to 62. So, the sample size needed is 62.

The Sample Size Needed to Estimate a Population Mean Within