Question

Fifteen coupens are numbered `1,2,3,...15` respectively. Seven coupons are selected at random one at a time with replacement The Probability that the largest number appearing on a selected coupon is 9 is : A. `((9)/(196))^(6)` B. `((8)/(15))^(7)` C. `((3)/(7))^(7)` D. None of these Select the correct answer from above options

Answer 1

Correct Answer - D Since, there are 15 possible cases for selecting a coupor and seven coupons are selected, the total number o cases of selecting seven coupons =`15^7` It is given that the maximum ·number on the selecte coupon is 9, therefore the selection is to be made from the coupons numbered 1 to 9. This can be made in r ways. Out of these `9^7` cases `8^7` does not contain the number 9. Thus, the favourable number of cases `=9^7-8^7` `therefore` Required probability `=(9^7-8^7)/(15^7)`