If I put nine pieces of paper, with a digit from 1-9 written on each one, into a hat, and pull 3 out without replacement, what is the likelihood that I will select three numbers that result in a winning tic-tac-toe?
1 | 2 | 3
---+---+---
4 | 5 | 6
---+---+---
7 | 8 | 9
Simple elmentary stuff, anyone who has studied probability will be able to answer it.
Submitting questions for the sake of getting promoted?
Anyway, the answer is:
P=[4x6x(1/9)x(1/8)x(1/7)]+[4x4x(1/9)x(1/8)x(1/7)]+[1x8x(1/9)x(1/8)x(1/7]
which is simply equal to 1/21+2/63+1/63=2/21.
Elementary.
