A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is
A. 1/4 B. 1/10
C. 7/15 D. 8/15

• Find the LCM of (15 and 20) units=60 units
  A's work for 4days=16 units
  B's work for 4days=12 units
  Total work for both in 4 days=16+12=28
  Hence the fraction of the work that is left=32/60=8/15
• 12 years agoHelpfull: Yes(22) No(11)
• 5/18
  (A+B) work=1/15+1/20=7/60
  4 days work=28/60
  left work=1-28/60=32/60=8/15
• 10 years agoHelpfull: Yes(15) No(1)
• A+B can do 1/15 +1/20 = 7/60
  for 4 days working together then work done is 4*7/60 =7/15
  the work left is = 1-7/15 = 8/15
• 8 years agoHelpfull: Yes(6) No(0)
• Total work done by them in one day = 1/15 + 1/20 = 7/60
  Total work done in 4 days = (7*4)/60
  Work left = 1-28/60 = 8/15
• 6 years agoHelpfull: Yes(0) No(0)
• A----15 days ,B----- 20 days. LCM(15,20)= 60. A----4 unit. B----- 3 unit. A+B= 28. Work that is left= (60-28)/60= 32/60= 8/15
• 6 years agoHelpfull: Yes(0) No(0)
• A can do work in 15 days
  
  B can do the same work in 20 days
  
  then work done by both in one day = 1/15+1/20=7/60.
  
  Work done by both in 4 days = 4*1/60= 28/60=7/15
  then the remainig work = 1-7/15= 8/15 ans
• 6 years agoHelpfull: Yes(0) No(0)