You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=72.7σ=72.7. You would like to be 95% confident...

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=72.7σ=72.7. You would like to be 95% confident that your estimate is within 4 of the true population mean. How large of a sample size is required?