A man, a boy and a woman can finish a work in 10 days, 15 days and 30 days, respectively. In how many days can the work be finished by a man, a woman and a boy when all of them work together?

Correct option is B

Efficiency of man, boy, and woman:
10 men = 15 boys = 30 women or 2 men = 3 boys = 6 women
Therefore, m : b : ω = 18 : 12 : 6 or 3 : 2 : 1
Total work = 30 units
Required days= = = 5 days