Purple Comet 2018 HS problem 16
Source:
March 19, 2020
combinatorics
Problem Statement
If you roll four standard, fair six-sided dice, the top faces of the dice can show just one value (for example, ), two values (for example, ), three values (for example, ), or four values (for example, ). The mean number of values that show is , where and are relatively prime positive integers. Find .