Multiple choice

Riya can complete a piece of work in 5 days, but with the help of her son she can do it in 3 days. Find the time taken by the son alone to complete the work?

  1. 7.5

  2. 13

  3. 11

  4. 9

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Riya alone: 5 days, so her rate = 1/5 per day. Riya + son: 3 days, so combined rate = 1/3 per day. Son's rate = (1/3) - (1/5) = 2/15 per day. Time for son alone = 1 ÷ (2/15) = 7.5 days. Option A is correct.

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