107. Cranky mower To start her old lawn mower, Rita has
S to pull a cord and hope for some luck. On any partic-
ular pull, the mower has a 20% chance of starting.
(a)
Find the probability that it takes her exactly 3 pulls to
start the mower.
(b) Find the probability that it takes her more than 6
pulls to start the mower.
108. 1-in-6 wins Alan decides to use a different strategy for
the 1-in-6 wins game of Exercise 90. He keeps buying
one 20-ounce bottle of the soda at a time until he gets
a winner.
Find the probability that he buys exactly 5 bottles.
(b) Find the probability that he buys at most 6 bottles.
Show
your work.
