Given: 15 coupons from 1 to 15. 7 coupons are selected with replacement
To find: the probability that the largest number appearing on a selected coupon is 9
Sol: According to the question,
Favourable numbers possible is {1, 2, 3, 4, 5, 6, 7, 8, 9}
Hence total possible ways of drawing 7 numbers with largest number being 9 = 97−87
Hence the probability that the largest number appearing on a selected coupon is 9 = 97−87157