For each situation in Exercise 7.9, find an interval that contains (approximately or exactly) 99.73 percent of

Question:

For each situation in Exercise 7.9, 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?
In Exercise 7.9
Suppose that we will take a random sample of size n from a population having mean µ and standard deviation s. For each of the following situations, find the mean, variance, and standard deviation of the sampling of the sample mean
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
Distribution
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