Q9) A company installs new central heating furnaces, and has found that for 15% of all installations a return visit is needed to make some modifications. Six installations were made in a particular week. Assume independence of outcomes for these installations.

a. What is the probability that a return visit was needed in all of these cases?

b. What is the probability that a return visit was needed in none of these cases?

c. What is the probability that a return visit was needed in more than one of these cases?