If A alone can do a piece of work in 15 days and B alone can do it in 10 days. A and B undertook to do it for Rs. 720. With the help of C they finished it in 5 days. How much is paid to C?

• 120 rupees is C's share
  
  In one day X can finish 1/15th of the work.
  
  In one day Y can finish 1/10th of the work.
  
  Let us say that in one day Z can finish 1/Zth of the work.
  
  When all the three work together in one day they can finish
  1/15 + 1/10 + 1/Z = 1/5th of the work.
  
  Therefore, 1/Z = 1/30.
  
  Ratio of their efficiencies = 1/15: 1/10: 1/30 = 2: 3: 1.
  Therefore Z receives 1/6th of the total money.
  
  According to their efficiencies money is divided as 240: 360: 120.
  
  Hence, the share of Z = Rs. 120.
• 12 years agoHelpfull: Yes(6) No(0)
• A's one day work is 1/15 and B's one day work is 1/10 days
  A and B together work in one day is 1/15+1/10=1/6 work
  (GIVEN)
  A, B and C together can work in one day =1/5 work
  Hence, C alone can do the work in one day =1/5-1/6=1/30 work
  Thus, C can alone do the work in 30 days.
  Now, the amount shall be shared by them according to their efficiency/work done.
  A has done the work in 5 days=5*1/15=1/3work
  B has done the work in 5 days=5*1/0=1/2 work
  c has done the work in 5 days=5*1/30=1/6 work
  C will have to be paid= 1/6*Rs.720=Rs.120
• 12 years agoHelpfull: Yes(4) No(1)