AMC8 2009 8, Problem 13

A three-digit integer contains one of each of the digits $1$, $3$, and $5$. What is the probability that the integer is divisible by $5$?

Solution: The three digit numbers are $135,153,351,315,513,531$. The numbers that end in $5$ are divisible are $5$, and the probability of choosing those numbers is $\fbox{\frac{1}{3}}$.

Answer: \frac{1}{3}