Question

We want to estimate the population mean within 5, with a 99% level of confidence. The population standard deviation is estimated to be 15. How large a sample is required? (Round up your answer to the next whole number.)

Answer 1

Answer: 60

Explanation:

Formula to calculate sample size (n):

`n=((\sigma* z^*)/(E))^2`

, where
`\sigma` = population standard deviation, E Margin of error , z* = critical value for the confidence interval.

As per given , we have

E =5

`\sigma=15`

Critical value for 99% confidence = 2.576

Then,

`n=((15*2.576)/(5))^2\\\\\Rightarrow\ n=59.721984\approx60`

So, Required sample size = 60 .