if A fills a tank in 30mins,and B fills the same tank in 20mins,and C emptys it in 40min ,if A,B,C works together how much time will the tank take to fill?

• 1/30+1/20-1/40=7/120
  so total time=120/7
  =17.14mins
• 12 years agoHelpfull: Yes(2) No(1)
• 1/30+1/20-1/40=1/x
  (80+120-60)/2400=1/x
  140/2400=1/x
  x=2400/140=120/7(ans)
  
  in previous sol. i did mistake in calculation
• 12 years agoHelpfull: Yes(2) No(2)
• 1/30+1/20-1/40=1/x
  80+120+60/2400=1/x
  260/2400=1/x
  x=2400/260=120/13(ans)
• 12 years agoHelpfull: Yes(1) No(3)
• 1/30+1/20-1/40=4+6-3/120
  =4/120=1/30 then total 30 hrs to fil a tank................
• 12 years agoHelpfull: Yes(0) No(2)