Hanuman can complete a bridge in 10 days and Ravan can complete the same bridge in 20 days. Now they are working together and they are completing the bridge in 20 days.
What is the contribution of Ravan in constructing the bridge ?
1.Half time work
2.2/4th of the bridge
3.1/3rd of the work
4.destructing the bridge

• Hanuman 1 days work=1/10
  Ravan 1 days work=1/20
  so the ratio of working the days Hanuman:ravan
  1/10:1/20
  20:10
  2:1
  total days take to working together=20;
  so contribution of Ravan=1/20*1/3
  =1/60
  so contribution of Hanuman=1/20*2/3
  =1/30
  so ravan construction is 1/3 of the work
  
  
• 11 years agoHelpfull: Yes(17) No(14)
• 4. destructing the bridge
• 11 years agoHelpfull: Yes(12) No(7)
• total work=lcm(10,20)
  hanus 1 day work=20/10=2 units
  ravans 1 day work=20/20=1 unit
  since they complete the bridge in 20 days therefore 1 unit work is to be done in 1 day
  so ravan destroys the bridge
  (2-1)*20=20 days
• 11 years agoHelpfull: Yes(8) No(1)
• some of the negative work is going on so answer is destructing the bridge
• 11 years agoHelpfull: Yes(5) No(2)
• Let the total work be 100 unit.
  hanuman per day work = 100/10 = 10 unit
  ravanan per day work = 100/20 = 5 unit
  
  Given, they complete the work in 20 days
  
  if both construct the bridge then, per day work is = 10 + 5 = 15 unit.
  and in 20 days they will do 20*15 = 300 unit of work, which is above the total unit of work.
  
  Hence ravan must be destructing the bridge, if so..
  total unit of work per day by them is 10-5 = 5 unit of work
  
  and in 20 days they do 20*5 = 100 unit of work , which is the required work.
  
  Hence, ravanan is destructing the bridge..
  
  i hope this is clear
• 8 years agoHelpfull: Yes(4) No(0)
• 4. destructing the bridge
• 11 years agoHelpfull: Yes(1) No(4)
• IS THE OBVIOUS ANSWER IN ANY SUCH CASES as when "a" & "b" takes X & Y tym to do it individually they should take >X &
• 10 years agoHelpfull: Yes(1) No(0)
• Hanuman 1 day=1/10 of the work done
  Ravan 1 day =1/20 of the work done
  working together for 1 day=1/10+1/20=3/20 of work done
  so if they work together for 20/3 days than can complete the task but in question it is written that they are taking 20 days so it contradicts with the results
  1/10-1/20 gives 20 days,so the answer is 4.
  
• 10 years agoHelpfull: Yes(1) No(0)
• 4. destructing the bridge
• 10 years agoHelpfull: Yes(1) No(0)
• 1/3 rd of the work is the answer.
• 9 years agoHelpfull: Yes(1) No(2)
• Here, Hanuman alone can complete in 10 days, whether Ravan alone can do it in 20 days.
  Again according to the question, both are working together and completing in 20 days.
  So, always there should be some destruction that's why they take 20 days together. Answer is 4.
• 9 years agoHelpfull: Yes(1) No(0)
• IS THE OBVIOUS ANSWER IN ANY SUCH CASES as when "a" & "b" takes X & Y tym to do it individually they should take >X &
• 10 years agoHelpfull: Yes(0) No(0)
• destroys the bridge is right answer
  
• 9 years agoHelpfull: Yes(0) No(0)