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Maths Puzzle
Q. TWO PIPES A AND B CAN FILL A TANK IN 15 MINUTES AND 20 MINUTES RESPECTIVELY. BOTH THE PIPES ARE OPENED TOGETHER BUT AFTER 4 MINUTES, PIPE a IS TURNED OFF. WHAT IS THE TOTAL TIME REQUIRED TO FILL THE TANK?
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- 10.66 min.
4 min. filling by A & B=4*[(1/15)+(1/20)]=4*(7/60)=7/15
Remaining tank to be filled by B only=1-(7/15)=8/15
Time(in Min.)required by B to fill=(8/15)/(1/20)=32/3 or 10.66 - 11 years agoHelpfull: Yes(3) No(2)
- Ans: 13 min 40 sec
In 4 min A+B fill the tank = 4 x ((1/15)+(1/20)) = 7/15
Remaining part is 8/15;
Pipe a is turned off, so remaining part is filled by Pipe B;
In 1min Pipe B fill 1/20, so
1 : (1/20) = x : (8/15) ---> x = 40/3 = 13 min 40 sec
- 11 years agoHelpfull: Yes(2) No(2)
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