"In this challenge, we practice calculating probability. Check out the [Tutorial](https://www.hackerrank.com/challenges/s10-mcq-1/tutorial) tab for a breakdown of ...

P(2 red, 1 black) = P(Red Red Black) + P(Red Black Red) + P(Black Red Red) = (4/7)(5/9)(1/2) + (4/7)(4/9)(1/2) + (3/7)(5/9)(1/2) ...