Suppose the shipping periods, in days, for medical equipment are normally distributed. If the population standard deviation is 3 days, what minimum sample size is needed to be 90% confident that the sample mean is within 1 day of the true population mean? 20.10 20.05 70.026 20.01 20.005 1.282 1.645 1.960 2.326 2.576 Use the table above for the z-score. Round only at the final step. Provide your answer below: medical equipment