A man, a woman and a boy can complete a job in 3,4 and 12 days respectively. How many boys must assist 1 man and 1 woman to complete the job in 1\4 of a day?

Explanation:

If they have to complete the 12 units work in 1\4 of day .

So it means their combined efficiency should be 48 /day.

(1 man + 1 woman)’s efficiency

= 4+3 = 7 units

unit left = 48−7 = 41 units

Now No. of boys required

= T.W\eff of a boy=41\1=41 boys