Concept: The question tests on the area of Rates(Time and Work)

Solution:

12 men take 36 days

12 men in 1 day do 1/36th of the work

1 man in 1 day does 1/1236

8 men in 1 day does 81/1236=1/54


18 women take 60 days

18 women in 1 day do 1/60 th of the work

1 woman in 1 day does 1/1860

20 women in 1 day does 201/1860=1/54


8 men and 20 women in 1 day does 1/54+1/54=1/27th of the work

Work done in 20 days = 201/27=20/27 th work

The remaining work = 1 – 20/27=7/27


Using the concept of MAN DAYS = M1T1/W1=M2T2/W2

M1 = 1, T1 = 1, W1 = Work done by 1 woman in 1 day1/1860

M2 = x, T1 = 4, W2 = Work done by x woman in 4 days to finish7/27th of the work


11/(1/1860)=x4/(7/27)

x=70


 Option A