Last year, the typical college student graduated with $27,200 in debt (The Boston Globe, May 27, 2012).

Question:

Last year, the typical college student graduated with $27,200 in debt (The Boston Globe, May 27, 2012). Let debt among recent college graduates be normally distributed with a standard deviation of $7,000.
a. What is the probability that the average debt of four recent college graduates is more than $25,000?
b. What is the probability that the average debt of four recent college graduates is more than $30,000?