It is known that 34% of people in the population have type O+ blood. Suppose that 3 people are sampled independently from the population, and let the random variable X represent how many of the three people in the sample have type O+ blood.

(a) Find the pdf of the random variable X. Show your calculations for each probability in your distribution.

(b) What is the expected number of people in the sample that have type O+ blood?

How would you do questions a and b?