Multiple choice

If 30 persons take 10 days to complete a certain work working 8 hours a day, then 40 persons should work how many hours a day so that the work is completed in 6 days?

  1. 12

  2. 8

  3. 6

  4. 10
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total work = 30 persons × 10 days × 8 hours/day = 2400 person-hours. This same work must be completed by 40 persons in 6 days. Let h be hours per day. Then 40 × 6 × h = 2400, so 240h = 2400, giving h = 10 hours per day. This is an inverse variation problem - more people means fewer hours needed.

Keep practicing — related questions