The study cited in Exercises 5.3.1 and 5.3.2 gives the following data on serum cholesterol levels in U.S. females:

Population Age Mean Standard Deviation A 20–29 183 37.2 B 30–39 189 34.7 Use these estimates as the mean m and standard deviation s for the respective U.S. populations.
Suppose we select a simple random sample of size 50 independently from each population. What is the probability that the difference between sample means
xB
xA will be more than 8?