1989 AMC 8 Problem 9

Attempt Problem 9 of the 1989 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1989 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

9.

There are 22 boys for every 33 girls in Ms. Johnson’s math class. If there are 3030 students in her class, what percent of them are boys?
12%12\%
20%20\%
40%40\%
60%60\%
6623%66\dfrac{2}{3}\%
Answer: C
Concepts:ratio and proportionpercentage
Small hint:
For every 22 boys there are 33 girls, so boys are 22 out of every 55 students
Big hint:
Convert the fraction 25\frac{2}{5} to a percent
Solution:
Boys make up 22 out of every 2+3=52 + 3 = 5 students, which is 25\frac{2}{5} of the class. The total of 3030 students is not even needed.
As a percent, 25=40%.\frac{2}{5} = 40\%.
Thus, the correct answer is C .
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