A contractor employed 210 men to build a house in 60 days. After 12 days , he was joined by 70 more men. In how many days will the remaining work be finished.

Question

anonymous · Answer

is it 36

anonymous · Answer

see 210 men were supposed to finish the remaining work in 60-12 =48 days
now 210+70 men will finish the work in x days say

anonymous · Answer

if more person joins the work should be finished early 
in other words men and time are inversely related 
hence
 we have 
210/280 =x/48  
or x= 210*48/280

parthkohli · Answer

After 12 days, 1/5 of the work had been completed. 

4/5 of the work was left.

Now it's pretty obvious that 70 people take $60 \times 3 = 180$ days because 70 people are 3 times less than 210. 

So $70 \times 4  = 280$ people take $180 \div 4 = 45$ days to complete the same work.

But 4/5 of the work is left, so it'd take $\dfrac{4}{5} \times 45$ days to complete the remaining work.