Fifteen coupons are numbered 1, 2, 3, …. 15. Seven coupons are selected at random one at a time with replacement. The probability that the largest number appearing on the selected coupon is 9, is
Answer & explanation
Correct answer: option 4
Total ways = 157.
For favorable ways, we must have 7 selected coupons numbered from 1 to 9 so that '9' is selected atleast once. Thus total number of favorable ways are, 97 - 87
⇒ Required probability = $\frac{9^7-8^7}{15^7}$.