A tank is filled in eight hours by three pipes K, L and M. Pipe K is twice as fa

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Question
A tank is filled in eight hours by three pipes K, L and M. Pipe K is twice as fast as pipe L, and L is twice as fast as M. How much time will pipe L alone take to fill the tank ?
Options
A. 32 hrs
B. 24 hrs
C. 28 hrs
D. 26 hrs

Correct Answer

28 hrs

Explanation

1/K + 1/L + 1/M = 1/8 (Given)
Also given that K = 2L and L = 2M
=> 1/2L + 1/L + 2/L = 1/8
=> (1 + 2 + 4)/2L = 1/8
=> 2L/7 = 8
=> L = 28 hours.

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Pipes and Cistern problems

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1. A water tank is filled in 5 hours by three pipes X, Y and Z the pipe Z is thrice as fast as Y and Y is twice as fast as X. How much time will pipe X alone take to fill the water tank?
Options
A. 60 hrs
B. 45 hrs
C. 40 hrs
D. 35 hrs

2. 3 pipes when opened for 3 hours can fill 3 buckets. How many buckets can 2 pipes open for 2 hours approximately fill?
Options
A. 2/3 buckets
B. 2 buckets
C. 1 bucket
D. 4/3 bucket

3. One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill tank in 36 min, then the slower pipe alone will be able to fill the tank in ?
Options
A. 85 min
B. 92 min
C. 187 min
D. 144 min

4. In what time would a cistern be filled by three pipes which diameters are 2 cm, 3 cm and 4 cm running together, when the largest alone can fill it is 58 minutes? The amount of water flowing in each pipe is proportional to the square of its diameter.
Options
A. 26 min
B. 32 min
C. 36 min
D. 42 min

5. Two pipes A and B can separately fill a cistern in 60 min and 75 min respectively. There is a third pipe in the bottom of the cistern to empty it. If all the three pipes are simultaneously opened, then the cistern is full in 50 min. In how much time, the third pipe alone can empty the cistern ?
Options
A. 85 min
B. 95 min
C. 105 min
D. 100 min

6. Three pipe P, Q and R can fill a tank in 12 minutes, 18 minutesand 24 minutes respectively. The pipe R is closed 12 minutesbefore the tank is filled. In what time the tank is full?
Options
A. 8 (5/13) hrs
B. 8 (4/13) hrs
C. 7 (4/13) hrs
D. 8 (6/13) hrs

7. Pipes A and B can fill a cistern in 15 hours together. But ifthese pipes operate separately A takes 40 hours less than Bto fill the tank. In how many hours the pipe A will fill thecistern working alone?
Options
A. 60
B. 20
C. 40
D. 15

8. 18 buckets of water fill a tank when the capacity of each bucket is 8 litres. How many buckets will be needed to fill the same tank, if the capacity of the bucket is 12 litres?
Options
A. 12
B. 13.5
C. 24
D. Data insufficient

9. A water tank is 2/5 th full. Inlet A can fill the tank in 12 minutes while an outlet pipe B can empty it in 6minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?
Options
A. It fills in 4.8 min
B. It empties in 4.8 min
C. It fills in 5.6 min
D. It empties in 5.6 min

10. A cistern has one inlet, L and one inlet, M. L takes 5 hours to fill the empty tank, when M is not open and M takes 8 hours to empty the full tank, if the tank is two fifth full, how much time will it take to fill the tank completely when both L and M are opened simultaneously? (in hours)
Options
A. 5 hours
B. 3 hours
C. 6 hours
D. 8 hours

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