Sixty-five percent of U.S. college graduates are employed in their field of study. You randomly select 20 U.S. college graduates and ask them whether they are employed in their field of study. Find the probability that the number who are employed in their field of study is 

(a) Exactly 15, 

(b) Less than 10, and 

(c) Between 20 and 35. Identify any unusual events. Explain.

Determine whether you can use a normal distribution to approximate the binomial distribution. If you can, use the normal distribution to approximate the indicated probabilities and sketch their graphs. If you cannot, explain why and use a binomial distribution to find the indicated probabilities.