For each of the following situations, find an interval that contains (approximately or exactly) 99.73 percent of all the possible sample means. In which cases must we assume that the population is normally distributed? Why?
(a) µ = 10, σ = 2, n = 25.
(b) µ = 500, σ = .5, n = 100.
(c) µ = 3, σ = .1, n = 4.
(d) µ = 100, σ = 1, n = 1,600.