A water filter takes 40 minutes to filter 20 liters of water Another filter of same specifications takes 30 minutes to filter the same amount of water If both the filters are used at the same time, then how long will it take them to filter 70 liters of water?
A) 30 minutes
B) 45 Minutes
C) 60 minutes
D) 90 minutes

• C) 60 minutes
  
  1 min. capacity of both the filters= (20/40)+(20/30)= 7/6 Liters
  So to filter 70 liters, time required= 70/(7/6)= 60 minutes
  
• 8 years agoHelpfull: Yes(7) No(0)
• 40 mins for 20 lit
  1 mint = 20/40 = 1/2 lit
  again , 1 min for other = 2/3 lit
  thus 1/2 +2/3 = 7/6
  time required for 70 lit is = 6/7 * 70 = 60 minutes (C)
• 7 years agoHelpfull: Yes(5) No(0)
• ans is option C...
• 8 years agoHelpfull: Yes(3) No(2)
• For the first filter,
  40 minutes take to fill 20 liters of water.
  Therefore,in 1 minute 20/40=1/2 liters of water can be filled.
  
  For the second filter,
  30 minutes take to fill 20 liters of water.
  Therefore,in 1 minute 20/30=2/3 liters of water can be filled.
  So,Two types together can fill in 1 minutes=(1/2+2/3)=7/6 liters.
  Now,if 7/6 liters can be filled in 1 minute then,
  70 liters can be filled in=(6/7)*70=60 minutes=1 hour.
• 5 years agoHelpfull: Yes(2) No(0)
• c)60 litres for 20 litres it takes
  (1/40)+(1/30)=70/1200 so work is 1200/70
  s0 for 70 litres it will take=(1200/70*1/20*70)=60
• 8 years agoHelpfull: Yes(0) No(1)
• 60 dont know
• 6 years agoHelpfull: Yes(0) No(0)
• C) 60 minutes
  
  1 min. capacity of both the filters= (20/40)+(20/30)= 7/6 Liters
  So to filter 70 liters, time required= 70/(7/6)= 60 minutes
• 5 years agoHelpfull: Yes(0) No(0)
• 60 minutes
• 5 years agoHelpfull: Yes(0) No(0)