Suppose the chance of getting flu is independent of each other. Suppose 20% of graduate school students nationwide develop influenza. Further, suppose we have a class of size 15. Let X be the number of students who get flu, calculate the following probabilities:

a Exactly 4 get influenza

b. No more than 4 get influenza

c. Less than 4 get influenza

d. How many students should the teacher expect to be sick with influenza that year?