1985 AJHSME Problems/Problem 5

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Solution

To get the fraction, we need to find the number of people who got grades that are "acceptable" (C and D is "acceptable!?") over the total number of people.

Finding the number of people who got acceptable grades is pretty easy. 5 people got A's, 4 people got B's, 3 people got C's and 3 people got D's. Adding this up, we just have $5+4+3+3 = 15$.

So we know the top of the fraction is 15. Only 5 people got "unacceptable" scores, so there are $15 + 5 = 20$ total score.

$\frac{15}{20}$ is our fraction. Of course, we're not done. You will usually have to reduce your fraction to lowest terms.

$\frac{15}{20} = \frac{3}{4}$.

(C) is the answer