Nine marbles numbered 1 to 9 are placed in a barrel and three are drawn out, without replacement. Determine -:
1. The probability that the three digit number formed from the marbles in the order drawn is divisible by (a) Five (b) Seven (c) Nine.
2. The probability that a three digit number can be formed by rearranging the marbles drawn, that is divisible by (a) Five (b) Seven (c) Nine.
(In reply to re(3): Partial Solution
Concurr with 9/14. Out of the 504 permutations, 72 are divisible by 7.
When mixing the numbers there are 108 repeats in the 432 (72*6) possibilities. This leaves 324 of 504 number combinations that can be rewritten to be divisible by 7. And as you showed 324/504 = 9/14
Posted by Leming
on 2006-04-25 14:19:49