Question

Determine the sample size for the estimate of for the following. E = 5.55 , σ = 18.22 , confidence level = 90 % . Round your answer up to the nearest whole number.

Answer 1

Solution :

Given that,

standard deviation = = 18.22

margin of error = E = 5.55

At 90% confidence level the z is ,

= 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

Z/2 = Z0.05 = 1.645

Sample size = n = ((Z/2 * ) / E)2

= ((1.645 * 18.22) / 5.55)2

= 29

Sample size = 29