Question

(S 9.2) a) In order to estimate the population mean, ?, to within 2 at 95% confidence, what is the minimum sample size required? (Assume ?=6.6).

Answer 1

Solution :

Given that,

standard deviation = = 6.6

margin of error = E = 2

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z_/2 = Z_0.025 = 1.960

Sample size = n = ((Z_/2 * ) / E)²

= ((1.960 * 6.6 ) / 2)²

= 41.8350

The minimum sample size = 42