1988 AJHSME Problems/Problem 23

Problem

Maria buys computer disks at a price of $4$ for <dollar/>$5$ and sells them at a price of $3$ for <dollar/>$5$. How many computer disks must she sell in order to make a profit of <dollar/>$100$?

$\text{(A)}\ 100 \qquad \text{(B)}\ 120 \qquad \text{(C)}\ 200 \qquad \text{(D)}\ 240 \qquad \text{(E)}\ 1200$

Solution

This is the equivalent of saying she buys $12$ for <dollar/>$15$ and sells $12$ for <dollar/>$20$, so for every dozen disks she sells, she profits <dollar/>$5$.

She needs to profit <dollar/>$100$, so she needs to sell $\frac{100}{5}=20$ dozen disks, which is $240\rightarrow \boxed{\text{D}}$

See Also

1988 AJHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 22
Followed by
Problem 24
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All AJHSME/AMC 8 Problems and Solutions

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