posted by anrt on .
In order to attract customers, an ice cream company has started a STAR game. Any person who collects four stars gets a free family size bucket of ice cream. Suppose that the probability of an ice cream pack contains a star is 0.3 (an ice cream pack cannot contain more than one star). Bob, ( a neighborhood child) has 1 star already. Find the probability that Bob has to buy 5 more ice cream packs to win the prize.