UKMT - Senior Mathematical Challenge - 2021 - 24 | Exact Science

24

Saba, Rayan, and Derin are cooperating to complete a task. When all three work together, it takes 5 minutes to complete the task. How many minutes does it take for Derin to complete the task on his own?

A. 21 B. 28 C. 35 D. 48 E. 105

Answer

E

SOLUTIOn

Solving using the rates at which Saba, Rayan, and Derin work gives that Derin takes 105 minutes to complete the task.

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