Question

A researcher wishes to estimate the number of hours family households spend on heating their homes. The standard deviation was said to be 5.9 with a standard error of 0.8. What size sample should be obtained if she wants to be 95% Confident?

Answer 1

Solution

standard deviation =s =   = 5.9

Margin of error = E = 0.8

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

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

n = ( 1.96*5.9/ 0.8)2

n =208.95

n=209 rounded