The Exponential Distribution · Exercise 38

According to the American Red Cross, about one out of nine people in the U.S. have Type B positive blood. Suppose the blood types of people arriving at a blood drive are independent. In this case, the number of Type B positive blood types that arrive roughly follows the Poisson distribution.

(a) If 100 people arrive, how many on average would be expected to have Type B positive blood?
(b) What is the probability that over 10 people out of these 100 have type B positive blood?
(c) What is the probability that more than 20 people arrive before a person with type B positive blood is found?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

OpenStax, Introductory Business Statistics 2e · §5.3 The Exponential Distribution · Exercise 38