8-1. For a normal population with known variance σ², answer the following questions: ( (a) What is the confidence level for the interval -2.50/√nd ( susx+2.50/√n? (b) What is the confidence level for the interval -2.496/√ +2.490/√n? (c) What is the confidence level for the interval -1.850/√n susx+1.850/√n? (- Is E t molding S