7.115) Dermatologists strongly recommend that people who are exposed to sunlight should either be covered up or put on sunscreen. Suppose that at a Florida condominium pool only a quarter of residents sit around the pool in the sun with no sunscreen.

a. What is the probability that in a random sample of 10 condo residents 3 or fewer have no sunscreen?

b. What is the expected number of residents who do not use sunscreen in a random sample of 100?