Consider a normal population distribution with the value of σ known. (a) What is the confidence level for the interval x − 2.81σ/√ n ≤ µ ≤ x + 2.81σ/√ n ? (b) What is the confidence level for the interval µ ≤ x + 2.00σ/√ n ? (c) What is the confidence level for the interval µ ≥ x − 1.96σ/√ n? (d) What value of zα/2 in the CI formula gives 99.7% confidence? (e) What value of zα/2 in the CI formula gives 75% confidence? (f) What value of zα would result in a 88% one-sided CI?