Question

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ = 67.4. You would like to be 99% confident that your estimate is within 4 of the true population mean. How large of a sample size is required?

Answer 1

We have given here,                  
                  
Population standard deviation =   67.4  
Margin of error =E=4  
Level of significance =   1-0.99=0.01  
Z critical value is (by using Z table)=   2.576  
Sample size formula is                   


=1884.05