A man, a woman and a boy can do a piece of work in 3 days, 4 days and 12 days respectively. How many boys should help a man and a woman to do the same piece of work in $1 \over 4$ day?

 [ A ]    41 [ B ]    48 [ C ]    52 [ D ]    61
 Answer : Option A Explanation : 1 man does the work in $1 \over 4$ day $1\over 3$ x $1 \over 4$ = $1 \over 12$ part1 woman does the work in $1 \over 4$ day $1 \over 4$ x $1 \over 4$ = $1 \over 16$ partTotal work done by one man and one woman = $1 \over 12$ + $1 \over 16$ = $4 + 3 \over 46$ = $7 \over 48$So, Remaining work = 1 - $7 \over 48$ = $41 \over 48$ partSo, The number of boys = $41 \over 48$ $\times$ 48 = 41 boys