Question

In estimating the mean monthly fuel expenditure, per household, a random sample of how many must be selected to be 99% confident and a population s. d. of 1.65, and margin of error, 5%.

Answer 1

Solution :

Given that,

Population standard deviation = = 1.65

Margin of error = E = 0.05

At 99% confidence level

= 1 - 99%  

= 1 - 0.99 =0.01

/2 = 0.005

Z/2 = Z0.005 = 2.576

sample size = n = [Z/2* / E] 2

n = [ 2.576 * 1.65 / 0.05 ]2

n = 7226.36

Sample size = n = 7327