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Jul. 30th, 2003 09:44 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
cailjOkay, math geeks, I have a question.
You have a certain number of numbers, X. How many unique sets of Y numbers can be created out of X? i.e., how many unique combinations of 5 numbers can be made if you have 25 numbers?
Or, to put it in more interesting terms, if you have 40 numbers, how many tickets must you buy in order to guarantee a win of all 6 numbers in a lottery? I remember there was a formula for this when I was in stats, but I don't remember what it was.
You have a certain number of numbers, X. How many unique sets of Y numbers can be created out of X? i.e., how many unique combinations of 5 numbers can be made if you have 25 numbers?
Or, to put it in more interesting terms, if you have 40 numbers, how many tickets must you buy in order to guarantee a win of all 6 numbers in a lottery? I remember there was a formula for this when I was in stats, but I don't remember what it was.
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no subject
Date: 2003-07-30 08:30 am (UTC)If there are N balls and you're picking P of them:
n!/p!(n-p)!
so:
40! / (6! * (40-6)!)
And I don't have a convenient way to do factorials here, so I leave it up to you to simplify.
I know for 49 ball lotto, it's about 14,000,000 combinations. so the odds are 1:14000000 for a single ticket to win.