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T10

Part of 2022 CCA Math Bonanza

Problems(1)

The last whale erased

Source:

4/27/2022
Evan, Larry, and Alex are drawing whales on the whiteboard. Evan draws 10 whales, Larry draws 15 whales, and Alex draws 20 whales. Michelle then starts randomly erasing whales one by one. The probability that she finishes erasing Larry's whales first can be expressed as pq\frac{p}{q}. Compute p+qp+q.
2022 CCA Math Bonanza Team Round #10