You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximate σ=28.5 You would like to be 99% confident that your estimate is within 4 of the true population mean. How large of sample size is required?
Do not round mid-calculation. However, use a critical value accurate to three decimal places — this is important for the system to be able to give hints for incorrect answers.