Hotels, Like Airlines, Often Overbook, Counting on the Fact That

Essay

Hotels, like airlines, often overbook, counting on the fact that some people with reservations will cancel at the last minute. A certain hotel chain has found that 20% of the reservations will not be used.
a. If we randomly selected 15 reservations, what is the probability more than 8 but fewer than 12 reservations will be used?
b. If four reservations are made, what is the chance fewer than two will cancel?