Pipe A can fill in 20 minutes and Pipe B in 30 mins and Pipe C can empty the same in 40 mins.If all of them work together, find the time taken to fill the tank

(a) 17 1/7 mins (b) 20 mins (c) 8 mins (d) none of these

• ans is 17 1/7
  (1/20+1/30-1/40)=7/120
  so, the time is 120/7 or 17 1/7
• 12 years agoHelpfull: Yes(19) No(2)
• 1 / (1/20+1/30-1/40) = 17 1/7
• 8 years agoHelpfull: Yes(1) No(0)
• A = 20
  B = 30
  C = -40
  LCM = 120
  => A = 6,TIMES
  B = 4
  C = -3
  => A+B-C = 7
  TIME TAKEN TO FILL THE TANK = 120/7 MINS = 17 1/7 MINS
• 8 years agoHelpfull: Yes(1) No(0)
• d.none of these
  correct ans is 120/13..
• 8 years agoHelpfull: Yes(0) No(2)
• Total time taken= 1/20 + 1/30 - 1/40 =7/120
  time= 120/7 = 17 1/7
• 7 years agoHelpfull: Yes(0) No(0)
• Lcm(20,30,40)=120->total work done
  1 min work=
  6+ 4 -3=7
  120/7=17 1/7 mins
• 7 years agoHelpfull: Yes(0) No(0)
• 17 1/17mins is the correct answer
• 4 years agoHelpfull: Yes(0) No(0)
• work=a+b-c
  =1/20+1/30-1/40
  =(6+4-3)/120
  =7/120
  time=inverse of work
  =120/7
  =17 1/7 mins
  so,option a
• 4 years agoHelpfull: Yes(0) No(0)
• total work=1/20+1/30-1/40=120/7
• 3 years agoHelpfull: Yes(0) No(0)