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having a bit of trouble getting my head around this:

Say I'm going to a card event with 370 people in total (including me) where we play 1 match and that match is 1v1 (so only 2 people play against each other).

I'm going with 4 friends.

What's the probability that I play against a friend.

I was thinking of the ways we could count 370 from 4 but I'm way off it has been a while since I've done a problem like this.

Any help is appreciated, thanks.

1 Answers 1

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Simply -

Probability = $\frac{\binom 41}{\binom{369}{1}} = \frac{4}{369}$

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    Or even more simply, they pick your opponent out of $369$ players, $4$ of whom are friends, so $\frac 4{369}$ – 2017-02-01
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    @Ross Millikan Yes we can write. I am add this. – 2017-02-01