1999 CEMC Gauss (Grade 7) Problems/Problem 18

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Problem

The results of the hair colour of $600$ people are shown in this circle graph. How many people have blonde hair?

$\text{(A)}\ 30 \qquad \text{(B)}\ 160 \qquad \text{(C)}\ 180 \qquad \text{(D)}\ 200 \qquad \text{(E)}\ 420$

Solution

The total percentage should add up to $100\%$, so the total percentage of individuals with blonde hair can be found by finding the total percentage of people with other hair colors, and subtracting the total from $100\%$.

This gives: $100\% - (32\% + 22\% + 16\%) = 30\%$

This means $30\%$ of the $600$ individuals shown in the results had blonde hair, which means:

$30\% \times 600 = 600 \times \frac{30}{100} = \boxed {\textbf {(C)} 180}$