5537. x̅=3.8, n=81, σ=4. Find a confidence interval with reliability γ=0.9 for the unknown mathematical expectation a of a normal distributed feature X of the general population, if the standard deviation σ=4 of the general population is known and the sample mean x̅=3.8 and sample size n=81 are given.

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