Online exam 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 4
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Subject :- Quantitative Aptitude
Chapter :- Pipers and Cistern-Test 4
Questions :- 25
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Pipes A and B can fill a cistern in 15 hours together. But if these pipes operate separately
A takes 40 hours less than B to fill the tank. In how many hours the pipe A will fill the
cistern working alone?
Correct
Let A takes x hours, then B = (x+40) hours
1/x + 1/(x+40) = 1/15
Solve, x = 20
Incorrect
Let A takes x hours, then B = (x+40) hours
1/x + 1/(x+40) = 1/15
Solve, x = 20
Question 2 of 25
2. Question
1 points
Three pipes A, B and C can fill the cistern in 10, 12, and 15 hours respectively. In how
much time the cistern will be full if A is operated for the whole time and B and C are
operated alternately which B being first?
Correct
In first hour, part of cistern filled is (1/10 +1/12) = 11/60
In second hour, part of cistern filled is (1/10 +1/15) = 1/6
So in 2 hours, part of cistern filled is 11/60 +10/60 = 21/60 = 7/20
now in 2*2 (4) hours, part of cistern filled is
(7/20)*2 = 14/20 = 7/10
now in the 5th hour, A+B’s turn which fill 11/60 in that hour, but the cistern remaining to be
filled is (1 – 7/10) = 3/10, since 3/10 is more
than 11/60, so after 5th hour remaining part to be filled is 3/10 – 11/60 = 7/60
now in 6th hour, (A+C)’s turn, it will fill remaining 7/60 in (7/60)*(6/1) = 7/10
so total 5 7/10 hours
Incorrect
In first hour, part of cistern filled is (1/10 +1/12) = 11/60
In second hour, part of cistern filled is (1/10 +1/15) = 1/6
So in 2 hours, part of cistern filled is 11/60 +10/60 = 21/60 = 7/20
now in 2*2 (4) hours, part of cistern filled is
(7/20)*2 = 14/20 = 7/10
now in the 5th hour, A+B’s turn which fill 11/60 in that hour, but the cistern remaining to be
filled is (1 – 7/10) = 3/10, since 3/10 is more
than 11/60, so after 5th hour remaining part to be filled is 3/10 – 11/60 = 7/60
now in 6th hour, (A+C)’s turn, it will fill remaining 7/60 in (7/60)*(6/1) = 7/10
so total 5 7/10 hours
Question 3 of 25
3. Question
1 points
A cistern is 1/4th full. Two pipes which fill the cistern in 15 minutes and 20 minutes
respectively are opened simultaneously. After 5 minutes, a third pipe which empties the full cistern in 30 minutes is also opened. In how many minutes the cistern will be full?
Correct
Since 1/4th is already filled, 3/4th is to filled now.
So
(1/15 + 1/20)*(5+x) – (1/30)*x = 3/4
(7/60)*5 + (7/60 – 1/30)*x = 3/4
(5/60)*x = 2/12
Solve, x = 2 mins
So total 7 minutes
Incorrect
Since 1/4th is already filled, 3/4th is to filled now.
So
(1/15 + 1/20)*(5+x) – (1/30)*x = 3/4
(7/60)*5 + (7/60 – 1/30)*x = 3/4
(5/60)*x = 2/12
Solve, x = 2 mins
So total 7 minutes
Question 4 of 25
4. Question
1 points
Pipes A, B and C which fill the tank together in 6 hours are opened for 2 hours
after which pipe C was closed. Find the number of hours taken by pipe C to fill the
tank if the remaining tank is filled in 7 hours.
Correct
1/A + 1/B + 1/C = 1/6
Now given that first all open for 2 hours, then C
closed and A+B completes in 7 hours, so
(1/A + 1/B + 1/C) *2 + (1/A + 1/B)*7 = 1
Put 1/A + 1/B = 1/6 – 1/C
(1/6 – 1/C + 1/C) *2 + (1/6 – 1/C)*7 = 1
2/6 + 7/6 – 7/C = 1
Solve, C = 14
Incorrect
1/A + 1/B + 1/C = 1/6
Now given that first all open for 2 hours, then C
closed and A+B completes in 7 hours, so
(1/A + 1/B + 1/C) *2 + (1/A + 1/B)*7 = 1
Put 1/A + 1/B = 1/6 – 1/C
(1/6 – 1/C + 1/C) *2 + (1/6 – 1/C)*7 = 1
2/6 + 7/6 – 7/C = 1
Solve, C = 14
Question 5 of 25
5. Question
1 points
Three pipes A, B and C can fill a cistern in 6 hours. After working at it together for 2
hours, C is closed and A and B can fill the remaining part in 6 hours. The number
of hours taken by C alone to fill the cistern is
Correct
A+B+C in 1h = 1/6
A+B+C in 2h = 2/6 = 1/3
Remaining = 1-1/3 = 2/3
A+B in 6hrs = 2/3
A+B in 1hr = 2/18
C alone to fill the cistern = 1/6 – 2/18 = 3-2/18 =
1/18
Incorrect
A+B+C in 1h = 1/6
A+B+C in 2h = 2/6 = 1/3
Remaining = 1-1/3 = 2/3
A+B in 6hrs = 2/3
A+B in 1hr = 2/18
C alone to fill the cistern = 1/6 – 2/18 = 3-2/18 =
1/18
Question 6 of 25
6. Question
1 points
Pipes A and B can fill a tank in 5 and 3 hrs respectively. Pipe C can empty empty it in 15
h. The tank is half full. All the three pipes are in operation simultaneously. After how much time the tank will be full ?
Correct
In 1 hr = 1/5+1/3 – 1/15 = 3+5-1/15 = 7/15
½ tank filled by 3 pipes = 15/7*1/2 = 15/14
=1(1/14)
Incorrect
In 1 hr = 1/5+1/3 – 1/15 = 3+5-1/15 = 7/15
½ tank filled by 3 pipes = 15/7*1/2 = 15/14
=1(1/14)
Question 7 of 25
7. Question
1 points
Two pipes A and B can fill a tank in 10 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 ?
Correct
A + B in 4 minute = 4 ( 1 / 10 + 1 / 20 ) =
4(2+1/20) = 12/20 = 3/5
Part remaning = 1 – ( 3 / 5 ) = 2 / 5
1 / 20 part is filled by B in 1 minute
2 / 5 part will be filled in = ( 20)* ( 2 / 5 ) =8 minutes
Total = 8+4 = 12m
Incorrect
A + B in 4 minute = 4 ( 1 / 10 + 1 / 20 ) =
4(2+1/20) = 12/20 = 3/5
Part remaning = 1 – ( 3 / 5 ) = 2 / 5
1 / 20 part is filled by B in 1 minute
2 / 5 part will be filled in = ( 20)* ( 2 / 5 ) =8 minutes
Total = 8+4 = 12m
Question 8 of 25
8. Question
1 points
Two pipes A and B can fill a tank in 6 hours and 5 hours respectively. If they are
turned on alternatively for 1 hour each, find the time in which the tank is full. (Assume
pipe A is opened first)
Correct
Total= 30, A = 30/6 =1/5, B = 30/5 =1/6
In 2 hrs = 5+6 =11
In 4hrs = 22
Remaining = 30-22 =8
1hr Pipe A = 8-5= 3,Remaining B = 3*1/6 =30min
Total = 5hrs 30min
Incorrect
Total= 30, A = 30/6 =1/5, B = 30/5 =1/6
In 2 hrs = 5+6 =11
In 4hrs = 22
Remaining = 30-22 =8
1hr Pipe A = 8-5= 3,Remaining B = 3*1/6 =30min
Total = 5hrs 30min
Question 9 of 25
9. Question
1 points
Pipes A, B and C can fill a tank in 3, 4 and 6 hours respectively. If all the pipes are
opened together and after 30 minutes pipes B and C are turned off, find the total time in
which the tank is full.
Correct
In 1 hr A, B, C = 1/3+1/4+1/6 = 8+6+4/24 =
18/24 = 6/8 = ¾
Filled in 30m = 3/8
Remaining = 1-3/8 =5/8
Pipe A = 3*5/8 = 15/8
Total = 15/8+1/2 = 15+4/8 = 19/8 = 2(3/8) hrs
Incorrect
In 1 hr A, B, C = 1/3+1/4+1/6 = 8+6+4/24 =
18/24 = 6/8 = ¾
Filled in 30m = 3/8
Remaining = 1-3/8 =5/8
Pipe A = 3*5/8 = 15/8
Total = 15/8+1/2 = 15+4/8 = 19/8 = 2(3/8) hrs
Question 10 of 25
10. Question
1 points
Two pipes M and N can fill a tank in 30 and 45 minutes respectively. If both the pipes
were open for few minutes after N was closed and the tank was full in 25 minutes, find the time for pipe N was open.
A cistern is filled by 3 pipes A, B and C with uniform flow. The second pipe B
takes 3/2 times the time taken by A to fill the tank, while C takes twice the time taken by B to fill the tank. If all the three pipes can fill the tank in 7 hours, find the time required by pipe A alone to fill the tank.
Two pipes P and Q can fill a tank in 8 hours. If only pipe P is open then it would
take 4 hours longer to fill the tank. Find how much longer would it take if only pipe Q is
open.
Two pipes P and Q can fill a tank in 20m and 30m respectively. If both the pipes are
opened simultaneously, after how much time should Q be closed so that the tank is full in
16minutes ?
A tap can fill a tank in 12 minutes and another tap can empty the tank in 6
minutes.If the tank is already full and then both the taps are opened the tank will be
Correct
1/12 – 1/6 = 1-2/12 = -1/12
Incorrect
1/12 – 1/6 = 1-2/12 = -1/12
Question 15 of 25
15. Question
1 points
Two taps can separately fill the tank in 18 m and 12 min respectively and when the waste
pipe is open, they can together fill the tank in 9 minutes.The waste pipe can empty the tank in
Two pipes can fill the tank in 4 hrs 5 hrs respectively while the third pipe can empty
the tank in 20 hrs, if all the pipes are opened together, then the tank will be filled in
Correct
1/4+1/5 -1/20 = 5+4-1/20 = 8/20
20/8 => 2(1/2)hrs
Incorrect
1/4+1/5 -1/20 = 5+4-1/20 = 8/20
20/8 => 2(1/2)hrs
Question 17 of 25
17. Question
1 points
10 buckets of water fill a taken when the capacity of each bucked is 14 liter. How many
buckets will be needed to fill the same tank, if the capacity of each bucket is 7 litres ?
Correct
10*14 = x*7
X = 10*14/7 = 20
Incorrect
10*14 = x*7
X = 10*14/7 = 20
Question 18 of 25
18. Question
1 points
A leak in the bottom of a tank can empty the full tank in 7 hours. An inlet pipe fills
water at the rate of 2 litres a minute. When the tank is full the inlet is opened and due to
the leak the tank is empty in 8 hours. The capacity of the tank in litres is
Correct
In 1 hr = 1/7 – 1/8 = 8-7/56 = 1/56
In 1 min = 1/(56*60) = 1/3360
Inlet pipe fill water at the rate of 2 liters a
minute = 2*3360 = 6720 litres
Incorrect
In 1 hr = 1/7 – 1/8 = 8-7/56 = 1/56
In 1 min = 1/(56*60) = 1/3360
Inlet pipe fill water at the rate of 2 liters a
minute = 2*3360 = 6720 litres
Question 19 of 25
19. Question
1 points
Two pipes P and Q can fill a tank in 6 hours and 8 hours respectively. If they are opened on alternate hours and if pipe P is opened first, in how many hours, the tank shall be full ?
Two pipes can fill a tank in 10 hours and 12 hours respectively while a third pipe
empties the full tank in 20 hours.If all the three pipes operate simultaneously, in how
much time will the tank be filled?
Correct
Net apart filled in 1 hour = (1/10+1/12-1/20)
= 8/60 = 2/15.
Tank will be full in = 15/2 hours =› 7 hrs 30 min.
Incorrect
Net apart filled in 1 hour = (1/10+1/12-1/20)
= 8/60 = 2/15.
Tank will be full in = 15/2 hours =› 7 hrs 30 min.
Question 21 of 25
21. Question
1 points
One pipe can fill a tank 4 times as fast as another pipe. If together the two pipes can fill
the tank in 15 minutes, then the slower pipe alone will be able to fill the tank in:
Correct
1/x+4/x = 1/15
5/x = 1/15
X/5= 15
X = 75 minutes
Incorrect
1/x+4/x = 1/15
5/x = 1/15
X/5= 15
X = 75 minutes
Question 22 of 25
22. Question
1 points
Bucket A has thrice the capacity as bucket B. It takes 20 turns for bucket P to fill
the empty drum. How many turns it will take for both the buckets A and B having each
turn together to fill the empty drum
Correct
A = 3B
A = 60, B = 20
No of turns = xy/x+y
No of turns = 60*20/20+60 = 1200/80 = 15 turns
Incorrect
A = 3B
A = 60, B = 20
No of turns = xy/x+y
No of turns = 60*20/20+60 = 1200/80 = 15 turns
Question 23 of 25
23. Question
1 points
Two pipes A and B would fill a cistern in 20 m and 30 min respectively, both pipes are kept open for 10 min and the first pipe be turned off after that the cistern may be filled in
Correct
10(1/20+1/30) = 10[3+2/60] = 50/60 = 5/6
Remaining part = 1-5/6 = 6-5/6 = 1/6
Second pipe = 30*1/6 = 5 min
Incorrect
10(1/20+1/30) = 10[3+2/60] = 50/60 = 5/6
Remaining part = 1-5/6 = 6-5/6 = 1/6
Second pipe = 30*1/6 = 5 min
Question 24 of 25
24. Question
1 points
Tap A can fill the empty tank in 12 hrs but due to leak in the bottom it is filled in 15 hrs.If
the tank is full ,then tap is closed.In how many hours the leak can empty the tank ?
Correct
1/12 – 1/15 = 5-4/60 = 1/60
Incorrect
1/12 – 1/15 = 5-4/60 = 1/60
Question 25 of 25
25. Question
1 points
Three pipes P,Q and R cal 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)x t,
So T=1 hr
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)x t,
