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Problem 235

AMC 10/12, early questions

Combinatorics Difficulty 3.9 Find the answer South African Mathematics Olympiad · South Africa

In a group of $108$ people, $1$ in $4$ of them has a pen and $1$ in $3$ has a pencil. What is the minimum possible number of people that have something to write with?

Your answer

Official solution

$36$ people must have a pen and $36$ must have a pencil. If all the people with pens also have pencils, this could be as few as $36$ people in all.

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