Couldn't give a title 2

In how many ways 18 identical balls can be used in 15 different cricket matches?


The answer is 680.

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1 solution

Each cricket match will require at least one ball, so we just to need to determine the number of ways of distributing the 3 3 "extra" (identical) balls amongst the 15 15 matches. With a k a_{k} representing the number of extra balls required for match k , k, the equation we must solve is

k = 1 15 a k = 3 \displaystyle\sum_{k=1}^{15} a_{k} = 3 for non-negative integers a k , 1 k 15. a_{k}, 1 \le k \le 15.

This is a stars and bars calculation, which according to Theorem two in the link has solution

( 3 + 15 1 3 ) = ( 17 3 ) = 680 . \dbinom{3 + 15 - 1}{3} = \dbinom{17}{3} = \boxed{680}.

nicely done sir

Tanishq Varshney - 6 years ago

Upvoted! Your Majesty:P

Yash Singhal - 6 years ago

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Hahaha. Thanks for the upvote. :)

Brian Charlesworth - 6 years ago

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