2011 AMC 12B Problem 8


Keiko walks once around a track at exactly the same constant speed every day. The sides of the track are straight, and the ends are semicircles. The track has width 66 meters, and it takes her 3636 seconds longer to walk around the outside edge of the track than around the inside edge. What is Keiko’s speed in meters per second?

(A) π3(B) 2π3(C) π(D) 4π3(E) 5π3\textbf{(A)}\ \frac{\pi}{3} \qquad \textbf{(B)}\ \frac{2\pi}{3} \qquad \textbf{(C)}\ \pi \qquad \textbf{(D)}\ \frac{4\pi}{3} \qquad \textbf{(E)}\ \frac{5\pi}{3}


Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.

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Category: AMC 12B
Points: 2
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