If 20 engineers and 20 workers can together construct a 20km road in 20 days . 40 engineers and 40 workers together construct 40 km road in how many days ? Somebody give proper explanation !!

• ans : 20 days
  20 docs and 20 engs can do work in 20 days...if we double them they can either do the same work in 10 days or double the work in same no of days.
• 10 years agoHelpfull: Yes(3) No(1)
• we need to find the no. of days of second set of data so keep it in left side. consider it d.
  now no. of engineers increasing so no. of dayswill decrease by the so 20/40 will be(20/40)
  no. of workers increasing so no. of days will decrease bythe ratio 20/40 again
  road to be made is increasing spo no. of days will increase by the ratio 40/20
  and the the given no. of days=10
  so now change in the no. of days= 10* (all the changing ratios)
  d=20*(20/40)*(20/40)*(40/20)
  we get 10 as the answer
  
• 10 years agoHelpfull: Yes(1) No(0)
• Ans.20 days. The answer is correct. I have some confusion regarding the solution. The solution is given as 20 X 20 = 400 man days for 20km road.
  i.e workers(20) X days(20) = 400 man-days , so for 40km road: 800 man-days are required. therefore 800/40 = 20 man-days.
• 5 years agoHelpfull: Yes(0) No(0)