. Compute the required sample size given the required confidence in the sample results is 99.74% (Z score of 3). The level of al
lowable sampling error is 5% and the estimated population standard deviation is unknown. Q/A6.1. Compute the required sample size given the required confidence in the sample results is 99.74% (Z score of 3). The level of allowable sampling error is 5% and the estimated population standard deviation is unknown.