A bag contains 7 red marbles, 8 blue marbles and 4 green marbles. If three marbles are drawn out of the bag, what is the probability, to the nearest 100oth, that all three
marbles drawn will be blue?

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?