2003 AMC 10A Problems/Problem 15
Revision as of 19:20, 4 November 2006 by Xantos C. Guin (talk | contribs) (added problem and solution)
Problem
What is the probability that an integer in the set is divisible by and not divisible by ?
Solution
There are integers in the set.
Since every 2nd integer is divisible by , there are integers divisible by in the set.
To be divisible by both and , a number must be divisible by .
Since every 6th integer is divisible by , there are integers divisible by both and in the set.
So there are integers in this set that are divisible by and not divisible by .
Therefore, the desired probability is