# Problem #1323

 1323 A traffic light runs repeatedly through the following cycle: green for $30$ seconds, then yellow for $3$ seconds, and then red for $30$ seconds. Leah picks a random three-second time interval to watch the light. What is the probability that the color changes while she is watching? $\mathrm {(A)} \frac{1}{63}\qquad \mathrm {(B)} \frac{1}{21}\qquad \mathrm {(C)} \frac{1}{10}\qquad \mathrm {(D)} \frac{1}{7}\qquad \mathrm {(E)} \frac{1}{3}$ This problem is copyrighted by the American Mathematics Competitions.
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