1999 CEMC Gauss (Grade 7) Problems/Problem 13

Problem

In the diagram, the percent of small squares that are shaded is


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$\text{(A)}\ 9 \qquad \text{(B)}\ 33 \qquad \text{(C)}\ 36 \qquad \text{(D)}\ 56.25 \qquad \text{(E)}\ 64$

Solution

Using the diagram, we can see that nine of the rectangles are shaded, and that the large square has a side length of $5$.

Since the large square has a side length of $5$, its area is $5^2 = 25$.

Therefore, the percentage of small squares that are shaded is $\frac{9}{25} = \frac{9 * 4}{25 * 4} = \frac{36}{100} = 36\%$. So, the answer is $\boxed {\textbf {(C)} 36}$.