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
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