Question

ats 6.1.47 Question Help k Determine the minimum sample size required when you want to be 95% confident that the sample mean is within one unit of the population mean and a = 12.9. Assume the population is normally distributed A 95% confidence level requires a sample size of I (Round up to the nearest whole number as needed.) th Contents

Answer 1

Solution :

Given that,

Population standard deviation = $\sigma$ = 12.9

Margin of error = E = 1

At 95% confidence level the z is ,

$\alpha$ = 1 - 95% = 1 - 0.95 = 0.05

$\alpha$ / 2 = 0.05 / 2 = 0.025

Z_$\alpha$/2 = Z_0.025 = 1.96

sample size = n = (Z_$\alpha$/2* $\sigma$ / E) ²

n = (1.96 * 12.9/ 1)²

n = 639.28

n = 640

Sample size = 640