4.According to the New York Times in 2009, the average cumulative debt of recent college graduates was about $22,500. Let the cumulative debt among recent college graduates be normally distributed with a standard deviation of $5,000.

a.Determine the probability that the cumulative debt of a randomly selected student will be less than $20,000. Show or explain your thinking.

b.Determine the probability that the cumulative debt of a randomly selected student will be more than $30,000.