There are two water tanks A and B, A is much smaller than B. While water fills at the rate of one litre every hour in A, it gets filled up like 10, 20, 40, 80, 160... in tank B.( At the end of first hour, B has 10 litres , second hour it has 20, and so on). If tank B is 1/32 filled after 21 hours, what is the total duration required to fill it completely?
(a) 26 hrs (b) 25 hrs (c) 5 hrs (d) 27 hrs

• There are two water tanks A and B, A is much smaller than B. While water fills at the rate of one litre every hour in A, it gets filled up like 10, 20, 40, 80, 160... in tank B.( At the end of first hour, B has 10 litres , second hour it has 20, and so on). If tank B is 1/32 filled after 21 hours, .
  then tank B is 1/16 filled after 22 hours
  tank B is 1/8 filled after 23 hours
  tank B is 1/4 filled after 24 hours
  tank B is 1/2 filled after 25 hours
  tank B is fuuly filled after 26 hours
• 13 years agoHelpfull: Yes(133) No(6)
• 21+log32=21+log(2^5)=26
• 13 years agoHelpfull: Yes(12) No(21)
• water gets filled in B like:
  10,20,30,40,......
  so its a G.P. with first term = 10 and common ratio = 2
  21st term of series = ar^20 = 10*2^20 this is equal to i/32 of the tank's full capacity
  hence full capacity of tank = 32*10*2^20 = 10*2^25
  which equals 26th term of series
  hence answer is 26th term.
  
• 8 years agoHelpfull: Yes(8) No(2)
• 1/32 filled in 21 hours
  1*2/32 =1/16 filled in 22 hours
  1*2/16 =1/8 filled in 23 hours
  1/4 filled in 24 hours
  1/2 filled in 25 hours
  1 filled in 26 hours
  
• 8 years agoHelpfull: Yes(6) No(0)
• Answer is 26 as in 21 hrs it has filled the tank upto 1/32 of its capacity so in 22 hrs it level will rise to 1/16 of its capacity and so on and till 26 hr it will get fully filled
• 10 years agoHelpfull: Yes(3) No(1)
• a. 26
  Since water in the tank is increasing in power of 2 so when the tank is 1/32 filled in 21 hours it will take 5 more hours to fill completely. 2^5=32
• 8 years agoHelpfull: Yes(1) No(0)
• answer is 26
• 9 years agoHelpfull: Yes(0) No(0)
• The data related to the first tank A is not necessary. As you can see, the capacity that gets filled in the tank B after each hour is doubled. So If the tank is 1/32nd part is full after 21 hours, it is 1/16th part full after 22 hours, 1/8th part full after 23 hours, 1/4th part full after 24 hours, 1/2 full after 25 hours, completely full after 26 hours.
• 7 years agoHelpfull: Yes(0) No(0)
• 1/32 in 21 hour
  2/32 =1/16 in 22 hour
  2/16=1/8 in 23 hour
  2/8 =1/4 in 24 hour
  2/4=1/2 in 25
  2/2=1 in 26 hour
• 4 years agoHelpfull: Yes(0) No(0)