You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=25.8σ=25.8. You would like to be 90% 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=25.8σ=25.8. You would like to be 90% confident that your estimate is within 2 of the true population mean. How large of a sample size is required?