Pipes & Cistern
Important Instructions
A cistern can be filled in 9 hours but it takes 10 hours due to a leak in its bottom. If the cistern is full, then the time that the leak will take to empty it is:
Answer: D
If A can fill a tank in x hours and B can fill a tank in y hours. Then the tank will be filled (empty) in = (xy / y-x) hours
Time taken by A = 9 hours
Time taken by B = 10 hours
Time taken by A and B = (9×10 / 10-9) = 90 hours.
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Which of the following fraction is the smallest?
Answer: B
12/14 = 0.857, 13/19 = 0.684, 17/21 = 0.8095 and 7/8 = 0.875
Since 0.684 is the smallest, so 13/19 is the smallest fraction.
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If one is added to the numerator of the fraction it becomes one. If one is added to the denominator of the fraction it becomes 1/2. The fraction is?
Answer: C
Let the fraction be x/y.
=> (x+1)/y = 1
=> x+1 = y—(1) x/(y-1) = 1/2
=> 2x = (y+1)—(2)
=>Equating (1) and (2)
=> x+1 = 2x-1
=>x=2
Substituting the value of x in (1)
=>y=3
=>2/3
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Two pipes A and B can fill a tank in 12 minutes and 15 minutes respectively. if both the pipes are opened simultaneously and pipe A is closed after 3 minutes, then how much more time will it take to fill the tank by pipe B .. ?
Answer: D
No answer description available for this question.
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One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill the tank in 36 minutes, then the slower pipe alone will be able to fill the tank in:
Answer: C
Let the slower pipe alone fill the tank in x minutes.
| Then, faster pipe will fill it in | x | minutes. |
| 3 |
 |
1 | + | 3 | = | 1 |
| x | x | 36 |
 |
4 | = | 1 |
| x | 36 |
x = 144 min.
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A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?
Answer: C
Suppose pipe A alone takes x hours to fill the tank.
| Then, pipes B and C will take | x | and | x | hours respectively to fill the tank. |
| 2 | 4 |
|
1 | + | 2 | + | 4 | = | 1 |
| x | x | x | 5 |
|
7 | = | 1 |
| x | 5 |
x = 35 hrs.
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A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time cistern will get filled ?
Answer: C
When we have question like one is filling the tank and other is empting it, then we subtraction as,
Filled in 1 hour = 1/4
Empties in 1 hour = 1/9
Net filled in 1 hour = 1/4 - 1/9
= 5/36
So cistern will be filled in 36/5 hours i.e. 7.2 hours
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Two friends A and B decided to work together and fill a pool of capacity 1000 liters. Using a bucket each, A fills at the rate of 4 liters every 3 minutes and B fills at 3 liters every 4 minute. What would be the total time required to fill the pool, given that they take a break of 3 minutes each time both of them put a bucket into the pool at the same instant ?
Answer: D
We are given that A fills the pool at the rate of 4 liters every 3 minutes and B fills the pool at the rate of 3 liters every 4 minutes.
=> Pool filled by A in 12 minutes = 4 x 4 = 16 liters
=> Pool filled by B in 12 minutes = 3 x 3 = 9 liters
=> Pool filled in 12 minutes = 16 + 9 = 25 liters
or we can say to fill 25 liters water, they will take 12 minutes.
Therefore to fill 1000 liters they will take (12*1000)/25 minutes i.e. 8 hours.
=> Since they will put a bucket at the same instant every 12 minutes. (LCM of 3 and 4 minutes = 12 minutes).
=> After every 12 minutes they will take rest for 3 minutes.
=> Overall (8*60)/12 i.e 40 times they take rest while working .
=> So every 12 minutes should be considered 15 (12+3) minutes for 40 times.
=> But after having taken 39 times . The pool of capacity 1000 liters will be filled.
=> Last 3 minutes must not be considered.
Therefore, to fill 1000 liters (25 x 40 liters), it would take (12*1000)/25 minutes i.e. 8 hours. + (39*3) minutes = 8 hrs. + 117 minutes
So ans is 9 hrs 57 minutes.
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There are two pipes which are functioning simultaneouly to fill a tank in 12 hours, if one pipe fills the tank 10 hours faster than other then how many hours second pipe will take to fill the tank ?
Answer: A
Lets suppose tank got filled by first pipe in X hours,
So, second pipe will fill the tank in X + 10 hours.
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Two pipes A & B can fill a cistern in 37 1/2 minutes and 45 minutes respectively. Both the pipes are opened. The cistern will be filled in just 30 minutes if if the pipe B is turned OFF after how many minutes ..?
Answer: B
No answer description available for this question.
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Topics
- Number System
- H.C.F. & L.C.M.
- Decimal Fractions
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