If one man or two women or four boys or five girls can finish a work in 39 days, then how many days will one man, one woman, one boy and one girl together take to finish the same work?
Answer & explanation
Correct answer: option 4
According to the question,
1M = 2W = 4B = 5G
Ratio of efficiency M : W : B : G
20 : 10 : 5 : 4
Total work = No. of labour x efficiency x no. of days
(using the efficiency of a man)
= 20 x 39 = 780
Efficiency of 1M + 1W + 1B + 1G = 20 + 10 + 5 + 4
= 39
Time taken = $\frac{Total\; work}{efficiency}$
= $\frac{780}{39}$ = 20 days