If B is Used for Half the Time and A & B Fill it Together :

A large tanker can be filled by two pipes A & B in 60 minutes & 40 minutes respectively. How many minutes will it takes to fill the tanker from empty state if B is used for half the time and A & B fill it together for the other half:

  1. 30 mins
  2. 15 mins
  3. 20 mins
  4. None of these
Anurag Mishra Professor Asked on 8th October 2015 in Maths.
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1 Answer(s)

Answer: (1) 30 mins

Explanation:-
Pipe A can be filled a tank = 60 min
Then, pipe A can be filled a tank in a min = 1/60 min

Pipe B can be filled a tank = 40 min
Pipe B can be filled a tank in a min = 1/40

Pipe A and B can be filled a tank in a min = (1/60 + 1/40)
= (2 + 3)/120
= 5/120
= 1/24

If B is used for half the time and A & B fill it together for the other half.
Then,  1 (1 /24 + 1/40)/2
= 1 (10 + 6)/240 x 2
= 16/240 x 2
= 2/30 x 2
= 1/30

Then, 30 min will it take to fill the tank.

Hence, the answer is (1) 30 mins.

Anurag Mishra Professor Answered on 11th October 2015.
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