Homework SourseA population is estimated to have a standard deviation of 12
A population is estimated to have a standard deviation of 12. We want to estimate the population mean within 2, with a 95 percent level of confidence.
| A population is estimated to have a standard deviation of 12. We want to estimate the population mean within 2, with a 95 percent level of confidence. |
Solution
Given a=1-0.95=0.05, Z(0.025) = 1.96 (from standard normal table)
So n=(Z*s/E)^2
=(1.96*12/2)^2
=138.2976
Take n=139
