. A tank is filled with water. In first hour 10 liters, second hours 20 liters, and third hour 40 liters and so on. If time taken to fill ¼ of the tank if 5 hours. What is the time taken to fill up the tank?
a) 5 B) 8 c) 7 d) 12.5

• Ans: 7 hrs
  
  1/4 in 5 hrs
  1/2 in 6 hrs
  full in 7 hrs.....
• 12 years agoHelpfull: Yes(20) No(3)
• 7 hrs
  1/4 in 5 hrs
  double of 1/4 ie 1/2 in 6th hr
  double of it in dats complete in 7th hour..
• 12 years agoHelpfull: Yes(5) No(2)
• At the end of each hour, amount of water gets doubled
  
  At the end of 5th hour,
  1
  4
  of the tank is filled
  
  At the end of 6th hour,
  1
  4
  ×
  2
  =
  1
  2
  of the tank is filled
  
  At the end of 7th hour,
  1
  2
  ×
  2
  =
  1
  tank is filled
  
  i.e., 7 hours are required to fill up the tank
• 4 years agoHelpfull: Yes(2) No(0)
• 1st hour 10 lit
  2nd hour 20 lit
  3rd hour 40 lit
  4th hour 70 lit
  5th hour 110 lit
  capacity of 1/4 of tank is 110 lit
  then capacity of full tank =220 lit
  same wise 6th hour 160 lit
  7th hour 220 lit
  hence 7 is the answer
• 7 years agoHelpfull: Yes(1) No(3)