For the random variables described below, which have binomial distributions?

a. You toss a balanced coin 50 times and count the number of heads.

b. Replacement heart valves have a probability of 0.77 of performing well for 15 years.It is reasonable to assume that values in different patients fail (or not) independently of each other.Let X be the number of patients in a group of 500 who will need another valve replacement within 15 years.

c. You deal 10 cards from a shuffled deck and count the number of red cards.