Problem N5727 probability theory sample size

Problem N5727 probability theory sample size

5727. Based on a sample of n=25, a sample average of piston ring diameters was calculated. Under the assumption of a normal distribution, determine with reliability γ=0.975 the accuracy δ with which the sample mean estimates the mathematical expectation, knowing that the standard deviation of the piston ring diameters is σ=4.

Additional information:

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)