25 men reap a field in 20 days. When should 15 men leave the work, if the whole field is to be reaped in 37 1/ 2 day after they leave the work?

25 men reap the field in 20 days
∴ 10 men can reap the feild in (20 x 25)/ 10 = 50 days.
When 15 men leave the work, 10 men remain and they can reap in 37¹/₂ days
= (37¹/₂)/ 50 = 3/4 of the field
Hence, all men must work till (1 - 3/4) = 1/4 of the field is reaped in 20/4 = 5 days.