A 10 hectare field is reaped by 2 men, 3 women and 4 children together in 10 days. If working capabilities of man, a woman and a child are in the ratio 5 : 4 : 2, then a 16 hectare field will be reaped by 6 men, 4 women and 7 children in

Let child's capability = 2 units/day. Then woman = 4 units/day, man = 5 units/day. First scenario: 2 men + 3 women + 4 children = 10 + 12 + 8 = 30 units/day. In 10 days, they complete 300 units, so 10 hectares = 300 units, meaning 1 hectare = 30 units. Second scenario: 6 men + 4 women + 7 children = 30 + 16 + 14 = 60 units/day. For 16 hectares = 480 units. Days needed = 480/60 = 8 days.