A bookstore has a website for which eighty percent (80%) of their book sales are to out-of-state customers and not subject to the collection of sales tax. The sample proportion, , of all sales to out-of-state customers from samples of size 100 will vary in repeated sampling. The sampling distribution for is approximately normal with a mean of 0.8 and a standard deviation of 0.04. Find the probabilities given in parts (a) through (d). Sketch the density curve and shade the area that represents the probability. Show all calculations for the probability.

a) What is the probability that between 0.72 and 0.88 of the sample is out-of-state customers?