# Pinball and Probability **URL:** \ **Category:** Factual Questions\ **Created:** [July 25, 1999, 1:33am UTC](https://boards.straightdope.com/t/pinball-and-probability/2147 "1999-07-25T01:33:00Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\ **Post date:** [July 25, 1999, 1:33am UTC](https://boards.straightdope.com/t/pinball-and-probability/2147/1 "1999-07-25T01:33:00Z")
When I was in middle school, I used to play a lot of pinball-- I was pretty good at it, but not so good at math. Anyway, after I had racked up a couple of credits, I’d play several games at once, because I thought I was increasing my chance of getting a free game by way of a match. It’s occurred to me today (I just bought my own pinball machine) that my math was way off-- if I used eight games to match two numbers, instead or eight different numbers, I increased the chance of one of the target numbers getting a match, (2/5, instead of 1/10) but that had nothing to do with winning a free game. Played one at a time, or four at a time, each game had just a 1/10 chance of matching-- assuming that the match numbers really are random. I don’t know enough about pinball to say that they are. So: eight numbers with a 1/10 chance each is the same as two numbers with a 2/5 chance each, right? (It’s been ten years since the one math class college required of me.) 2 x 2/5 = 4/5, and 8 x 1/10 = 4/5 also. Did I set that up right? Can someone who’s better at math confirm my current thinking? ## Also, anyone out there know for sure if the match numbers in pinball are really random? * * * –Rowan Shopping is still cheaper than therapy. --my Aunt Franny