Question

If 2 men or 3 boys take 40 hrs to do a certain piece of work ,how long will 4 men and 9 boys working together take to complete the work?

Answer 1

2 men = 3 boys

1 men = 3/2 boys

so 4 men = 3/2 × 4 boys = 6 boys

now the problem is

3 boys can do a work in 40 hours

what time will 4 men and 9 boys take to complete the work

it means that 4 men = 6 boys

so 4 men and 9 boys = 6 boys + 9 boys = 15 boys

so the solution is,

3 boys = 40 hours

1 boy = 40 × 3 = 120 hours

15 boys = 120/15 hours = 8 hours.

Answer 2

your answer is 8 hours