Who wants to find the probability of winning the lottery ;D ! Okay, so in a quick draw game, you have to choose 4 numbers, anywhere from 1-80 (but no repeats-- you can't choose 11 twice). The order of the number doesn't matter. Ten numbers will be called out, and if all four of your numbers are in there, you get the grand prize; if three of your numbers are there, you get the second place prize, and if two of your numbers are there, you still get a prize. Find the probability of winning anything.

Question

anonymous · Answer

I know that it should come out to 1:3.86, but I don't know how to find that.

phi · Answer

I imagine white ping pong balls, labeled 1 through 80. Now randomly choose 4 of them and mark them red. The problem nows sounds like what is the probability of choosing 4 red balls from a population of 76 white balls and 4 red balls, using 10 draws. added to prob of choosing 3 red balls plus prob of choosing 2 red balls You can use http://en.wikipedia.org/wiki/Hypergeometric_distribution#Definition but I do not get 1: 3.86