Online Quiz in Pipes and Cistern For Quantitative Aptitude for Competitive exams like IBPS BANK PO/Clerical,SBI,RRB,SSC,LIC,UPSC-CSAT,SCRA.MAT,CMAT,MBA,SNAP,CAT,NTSE,CLAT
Pipes and Cistern-Test 3
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Subject :- Quantitative Aptitude
Chapter :- Pipers and Cistern-Test 3
Questions :- 25
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A pipe can empty a tank in 60 minutes alone. Another pipe whose diameter is twice the
diameter of first pipe is also opened. Now find the time in which both pipe will empty the
tank together.
Correct
Time taken by pipe to empty the tank is inversely proportional to cross- sectional area.
So, time taken by second pipe will be = 60/4 =
15 min (πr2 = 1/60 and for second pipe 4πr2 = 1/T so we get T = 15 min)
Time taken by both to empty the pipe = (60*15)/75 = 12
Incorrect
Time taken by pipe to empty the tank is inversely proportional to cross- sectional area.
So, time taken by second pipe will be = 60/4 =
15 min (πr2 = 1/60 and for second pipe 4πr2 = 1/T so we get T = 15 min)
Time taken by both to empty the pipe = (60*15)/75 = 12
Question 2 of 25
2. Question
1 points
Two pipes P and Q can fill a tank in 10 min and 12 min respectively and a waste pipe
can carry off 12 litres of water per minute. If all the pipes are opened when the tank is full
and it takes one hour to empty the tank. Find the capacity of the tank.
Correct
Let the waste pipe take ‘T’ time to empty the tank.
(1/10 + 1/12 – 1/T)*60 = -1
We will get T = 5 min
So capacity = 5*12 = 60ltr
Incorrect
Let the waste pipe take ‘T’ time to empty the tank.
(1/10 + 1/12 – 1/T)*60 = -1
We will get T = 5 min
So capacity = 5*12 = 60ltr
Question 3 of 25
3. Question
1 points
Two pipes P and Q can fill a tank in 36 and 24 minutes respectively. If both the pipes
are opened simultaneously, after how much time pipe Q should be closed so that tank is
full in 30 minutes.
Correct
Let after T time, Q is closed, (1/36 + 1/24)*T +
(1/36)*(30 – T) = 1
Incorrect
Let after T time, Q is closed, (1/36 + 1/24)*T +
(1/36)*(30 – T) = 1
Question 4 of 25
4. Question
1 points
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. Both the pipes
are opened together but after 5 minutes pipe B is closed. What is the total time required to fill the tank
Correct
(1/20 + 1/30)*5 + (1/20)*T = 1
total time = T + 5 min
Incorrect
(1/20 + 1/30)*5 + (1/20)*T = 1
total time = T + 5 min
Question 5 of 25
5. Question
1 points
Three pipes P, Q and R can fill a tank in 12, 15 and 20 minutes respectively. If pipe P
is opened all the time and pipe Q and R are opened for one hour alternatively. The tank
will be full in
Correct
(1/12 + 1/15) + (1/12 + 1/20) = 17/60 (in 2 hrs
this much tank is filled)
so in 6 hrs 51/60 is filled. Remaining, 9/60 =
(1/12 + 1/15)*t, so T = 1hr
so total = 6 + 1 = 7 hr
Incorrect
(1/12 + 1/15) + (1/12 + 1/20) = 17/60 (in 2 hrs
this much tank is filled)
so in 6 hrs 51/60 is filled. Remaining, 9/60 =
(1/12 + 1/15)*t, so T = 1hr
so total = 6 + 1 = 7 hr
Question 6 of 25
6. Question
1 points
A cistern can be filled by a pipe in 6 hours. A leak is developed at the bottom due to
which it takes 2 hours more to fill the cistern. Find the time taken by the leak to empty the cistern when the cistern is full.
Correct
Incorrect
Question 7 of 25
7. Question
1 points
Two pipes can separately fill the tank in 15 hrs and 30 hrs respectively. Both the pipe
are opened and when the tank is 1/3 full a leak is developed due to which 1/3 water
supplied by the pipe leaks out. What is the total time to fill the tank?
Correct
(1/15 + 1/30)*T1 = 1/3, T1 = 10/3 hr
now after leak is developed, [(1/15 + 1/30) –
(1/3)*(1/15 + 1/30)]*T2 = 2/3
T2 = 10 hr. So total time = 10 + 10/3 = 40/3 hr
Incorrect
(1/15 + 1/30)*T1 = 1/3, T1 = 10/3 hr
now after leak is developed, [(1/15 + 1/30) –
(1/3)*(1/15 + 1/30)]*T2 = 2/3
T2 = 10 hr. So total time = 10 + 10/3 = 40/3 hr
Question 8 of 25
8. Question
1 points
Pipe P is 4 times as fast as Q in filling a tank. If P takes 20 minutes to fill a tank, then
what is the time taken by both the pipe P and Q to fill the tank?
Correct
P takes 20 minutes and it is 4 times faster than
Q, it means Q will take 80 minutes to fill the tank.
(1/20 + 1/80)*t = 1. We get t = 16
Incorrect
P takes 20 minutes and it is 4 times faster than
Q, it means Q will take 80 minutes to fill the tank.
(1/20 + 1/80)*t = 1. We get t = 16
Question 9 of 25
9. Question
1 points
In what time a cistern is filled by three pipes of diameter 2 cm, 4 cm and 6 cm
respectively. If the time taken by largest pipe to fill the tank is 40 minutes. Amount of water flowing through the pipe is proportional to the diameter of the pipe
Correct
Larger the cross-section area less will be time taken by pipe to fill the tank.
36/16 = T/40, T = 90min (for 4 cm pipe)
similarly for 2 cm pipe time taken will be = 360 min
Total time = (1/360 + 1/90 + 1/40) = 1/p, so we
get P = 25.5/7 minutes
Incorrect
Larger the cross-section area less will be time taken by pipe to fill the tank.
36/16 = T/40, T = 90min (for 4 cm pipe)
similarly for 2 cm pipe time taken will be = 360 min
Total time = (1/360 + 1/90 + 1/40) = 1/p, so we
get P = 25.5/7 minutes
Question 10 of 25
10. Question
1 points
Two pipes P and Q can fill a tank in 20hrs and 25hrs respectively while a third pipe R
can empty the tank in 30hrs. If all the pipes are opened together for 10hrs and then pipe R is closed then in what time the tank can be filled.
Correct
(1/20 + 1/25 – 1/30)*10 + (1/20 + 1/25)*x = 1
We get x = 130/27, so total time to fill the tank =
130/27 + 10 = 400/27 hrs
Incorrect
(1/20 + 1/25 – 1/30)*10 + (1/20 + 1/25)*x = 1
We get x = 130/27, so total time to fill the tank =
130/27 + 10 = 400/27 hrs
Question 11 of 25
11. Question
1 points
There are three taps A, B and C which can fill a tank in 12hrs, 15hrs and 30 hrs
respectively. If the tap A is opened first, after one hour tap B was opened and after 2 hours from the start of A, tap C is also opened. Find the time in which the tank is full.
Correct
In first hour only A is opened, in the next hour A and B are opened and in the third hour A, B and C are opened.
So, in three hours (3/12 + 2/15 + 1/30) = 25/60
tank is already filled.
Now, 25/60 = (1/12 + 1/15 + 1/30)*t
T = 25/11. Total time = 3 + 25/11 = 58/11 hours
Incorrect
In first hour only A is opened, in the next hour A and B are opened and in the third hour A, B and C are opened.
So, in three hours (3/12 + 2/15 + 1/30) = 25/60
tank is already filled.
Now, 25/60 = (1/12 + 1/15 + 1/30)*t
T = 25/11. Total time = 3 + 25/11 = 58/11 hours
Question 12 of 25
12. Question
1 points
Three pipes P, Q and R can fill the tank in 5, 10 and 15 minutes respectively. If all the
pipes are opened together and pipe Q is turned off 5 minutes before the tank is fill.
Then find the time in which the tank will full.
Correct
Let total time taken by the pipes is T hrs, then
(1/5 + 1/10 + 1/15)*(T – 5) + (1/5 + 1/15)*5 = 1
Incorrect
Let total time taken by the pipes is T hrs, then
(1/5 + 1/10 + 1/15)*(T – 5) + (1/5 + 1/15)*5 = 1
Question 13 of 25
13. Question
1 points
A pipe can fill a tank in 20 minutes but due to a leak develop at the bottom of the
tank, 1/5 of the water filled by the pipe leaks out. Find the time in which the tank is filled.
Correct
Amount of tank filled by the pipe in one minute
= 1/20 and due to leakage 1/5 of 1/20 leaks out
so, [1/20 – (1/5)*(1/20)]*T = 1
We get T = 25
Incorrect
Amount of tank filled by the pipe in one minute
= 1/20 and due to leakage 1/5 of 1/20 leaks out
so, [1/20 – (1/5)*(1/20)]*T = 1
We get T = 25
Question 14 of 25
14. Question
1 points
A bathing tub can be filled by a cold pipe in 15 minutes and by a hot pipe in 10 minutes.
Ramesh opened both the tap and leaves the bathroom and returns at the time when the
tub should be full. He observed that a waste pipe is opened at the bottom, he now closes it. Now the tub will take more 5 minutes to fill the tank, find the time in which the leak can empty the tank.
There are 10 taps connected to a tank. Some of them are waste pipe and some of
them are water pipe. Water pipe can fill the tank in 15 hours and waste pipe can empty
the tank in 30 hours. Find the number of waste pipes if the tank is filled in 6 hours.
Correct
Let water pipes are x and waste pipe are Y.
x + y = 10
(x/15 – y/30)*6 = 1
Solve both equation to get x and y
Incorrect
Let water pipes are x and waste pipe are Y.
x + y = 10
(x/15 – y/30)*6 = 1
Solve both equation to get x and y
Question 16 of 25
16. Question
1 points
Pipe A is 4 times as fast as B in filling a tank. If A takes 20 minutes to fill a tank, then
what is the time taken by both the pipe A and B to fill the tank?
Correct
A takes 20 minutes and it is 4 times faster than B, it means B will take 80 minutes to fill the tank.
(1/20 + 1/80)*t = 1. We get t = 16
Incorrect
A takes 20 minutes and it is 4 times faster than B, it means B will take 80 minutes to fill the tank.
(1/20 + 1/80)*t = 1. We get t = 16
Question 17 of 25
17. Question
1 points
Pipe A is 4 times faster than pipe B and takes 45 minutes less to fill a tank. When both
the pipes are opened together than the time in which the tank will be full.
Correct
Let A take X minute to fill a tank then B will take 4x time.
4x – x = 45 (given), X = 15.
Time taken to fill the tank together = (1/15 +1/60)*t =1
T = 12 minute
Incorrect
Let A take X minute to fill a tank then B will take 4x time.
4x – x = 45 (given), X = 15.
Time taken to fill the tank together = (1/15 +1/60)*t =1
T = 12 minute
Question 18 of 25
18. Question
1 points
Two pipes P and Q can fill a tank in 20 minutes and 30 minutes respectively. There is
a waste pipe which withdraws water at the rate of 8 litres per minute. Now the tank is
full and If all the pipes are opened simultaneously the tank is emptied in 60 minutes. Find the capacity of the tank.
Correct
(1/20 + 1/30 – 1/t)*60 = -1
‘-1’ is taken because the work is negative. T is
the time taken by the waste pipe to empty the
tank alone. We will t = 10
So capacity = 10*8 = 80ltr
Incorrect
(1/20 + 1/30 – 1/t)*60 = -1
‘-1’ is taken because the work is negative. T is
the time taken by the waste pipe to empty the
tank alone. We will t = 10
So capacity = 10*8 = 80ltr
Question 19 of 25
19. Question
1 points
There are 4 filling pipes and 3 emptying pipes capable of filling and emptying in 12
minutes and 15 minutes respectively. If all the pipes are opened together and as a result they fill 10 litres of water per minute. Find the capacity of the tank.
Correct
(4/12 – 3/15)*t = 1
t = 15/2 minute – in this time the tank will be
filled. So the capacity = (15/2)*10 = 75 litre
Incorrect
(4/12 – 3/15)*t = 1
t = 15/2 minute – in this time the tank will be
filled. So the capacity = (15/2)*10 = 75 litre
Question 20 of 25
20. Question
1 points
Two taps can separately fill the tank in 10m and 15min respectively. They fill the tank in
12 minutes when a third pipe which empties the tank is also opened. What is the time
taken by the third pipe to empty the whole tank?
Correct
1/10 + 1/15 – 1/x = 1/12
Solve, x = 12
Incorrect
1/10 + 1/15 – 1/x = 1/12
Solve, x = 12
Question 21 of 25
21. Question
1 points
Two pipes A and B can fill a tank in 12 hours and 15 hours respectively. If they are
opened on alternate hours with pipe A opened first, then in how many hours the tank will be full?
Correct
A = 12 hours, B = 15 hours
Total work = LCM(12,15) = 60
So efficiency of A = 60/12 = 5, efficiency of B = 60/15 = 4
2 hrs work of (A+B) = 5+4 = 9
2*6(12) hours work of (A+B) = 9*6 = 54
So remaining work = 60-54 = 6
Now A’s turn at 13th hour, he will do remaining
work(6) in 6/12 hr
So total 12 1/2 hrs
Incorrect
A = 12 hours, B = 15 hours
Total work = LCM(12,15) = 60
So efficiency of A = 60/12 = 5, efficiency of B = 60/15 = 4
2 hrs work of (A+B) = 5+4 = 9
2*6(12) hours work of (A+B) = 9*6 = 54
So remaining work = 60-54 = 6
Now A’s turn at 13th hour, he will do remaining
work(6) in 6/12 hr
So total 12 1/2 hrs
Question 22 of 25
22. Question
1 points
Pipes P and Q can fill the tank in 24 minutes and 32 minutes respectively. Both
piped are opened together. To have the tank full in 18 minutes, after how many minutes
the pipe P must be closed?
Correct
P is to be closed before 18 minutes, let it is
closed after x minutes, then Q worked for all 18
minutes. So,
(1/24)*x + (1/32)*18 = 1
Solve, x = 10.5
Incorrect
P is to be closed before 18 minutes, let it is
closed after x minutes, then Q worked for all 18
minutes. So,
(1/24)*x + (1/32)*18 = 1
Solve, x = 10.5
Question 23 of 25
23. Question
1 points
Three pipes, A, B and C are opened to fill a tank such that A and B cam fill the tank
alone in 36 min. and 45 min. respectively and C can empty it in 30 min. After 6 minutes the emptying pipe is closed. In how many minutes the tank will be full in this way?
Correct
Let the tank full in x minutes, then A and B
opened for x minutes and C for 6 minutes.
(1/36 + 1/45)*x – (1/30)*6 = 1
(1/20)*x = 6/5
Solve, x = 24
Incorrect
Let the tank full in x minutes, then A and B
opened for x minutes and C for 6 minutes.
(1/36 + 1/45)*x – (1/30)*6 = 1
(1/20)*x = 6/5
Solve, x = 24
Question 24 of 25
24. Question
1 points
A and B are pipes such that A can empty the tank in 60 minutes and B can fill in 30
minutes. The tank is full of water and pipe A is opened. If after 18 minutes, pipe B is also
opened, then in how much total time the tank will be full again?
Correct
Emptying pipe A is opened first for 18 minutes, so in 18 minutes the part of tank it has emptied is (1/60)*18 = 9/30
Now filling pipe is also opened, now since only
9/30 of the tank is empty so 9/30 is only to be
filled by both pipes, let it take now x minutes, so
(1/30 – 1/60)*x = 9/30
Solve, x= 18
So total = 18+18 = 36 minutes [total time is
asked – 18 minutes when emptyimh pipe was only opened, 18 minutes when both were
operating.]
Incorrect
Emptying pipe A is opened first for 18 minutes, so in 18 minutes the part of tank it has emptied is (1/60)*18 = 9/30
Now filling pipe is also opened, now since only
9/30 of the tank is empty so 9/30 is only to be
filled by both pipes, let it take now x minutes, so
(1/30 – 1/60)*x = 9/30
Solve, x= 18
So total = 18+18 = 36 minutes [total time is
asked – 18 minutes when emptyimh pipe was only opened, 18 minutes when both were
operating.]
Question 25 of 25
25. Question
1 points
Two pipes A and B can alone fill a tank in 20 minutes and 30 minutes respectively. But
due to a leak at the bottom of tank, it took 3 more minutes to fill the tank. In how many
hours, the leak can alone empty the full tank?
Correct
A and B can fill tank in (1/20 + 1/30) = 1/12 so
12 minutes.But it took 3 more minutes, this means the tank
got full in 12+3 = 15 minutes
So (1/20 + 1/30 – 1/x) = 1/15
Solve, x = 60
Incorrect
A and B can fill tank in (1/20 + 1/30) = 1/12 so
12 minutes.But it took 3 more minutes, this means the tank
got full in 12+3 = 15 minutes
So (1/20 + 1/30 – 1/x) = 1/15
Solve, x = 60
