This calculator is appropriate when you know the population standard deviation, sigma and are given the Margin of Error E and the Confidence Level, c.
Example: You are asked to find the minimum number of people to include in a sample to determine the population mean. The population standard deviation has been determine to be 0.35 inches. The required confidence level is 99% and the required Margin of Error is 0.1.
Download a copy of the Excel workbook: Min Sample Size for CI given c, sigma, and E V1.02