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 Partial Solution by tomarken)

Repeat of other comments:

Small concern with your answers to (c).

If the first two numbers total to 9 (i.e. 3 and 6) a zero marble is not available to keep the probability as 1/7.

If the first two numbers are 2 and 5, then another 2 is needed but not available.

I'm concerned that this may be a brute force type of problem.

Edited on April 25, 2006, 1:24 pm

Posted by Leming on 2006-04-25 13:22:34