5 workers construct a wall in 6 hours. How many hours are required to construct the same wall by 3 workers?

10 hours

8 hours

9 hours

None of these

Work done is constant.

If 6 workers take 5 hours, total work = 6 × 5 = 30 worker-hours.

For 3 workers, time = 30 ÷ 3 = 10 hours.