Fifteen coupons are numbered 1 to 15. Seven coupons are selected at random one at a time with replacement then What is the probability that the largest number appearing on the selected coupon is 9?
I understood that it will be $9^7-8^7$ (excluding cases with 8 as maximum) But i was also thinking this way
first i fill 1 place out of 7 by 9 and then fill remaining 6 places with any digit from 1 to 9. So total favourable cases = 7C1 * $9^6$.
But these are not equal numerically. What is wrong in 2nd way. Pls clarify.