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Pipes & Cisterns — PPSC previous year questions

All 6 Pipes & Cisterns questions the Punjab PSC asked between 2022 and 2024, each with a worked answer and the exam it came from. First 10 free to read.

Questions
6
Years covered
2022–2024
Papers
8
Repeated
0

The 6 it asks most

Free to read, with the worked answer and the exam each one came from. The book prints this topic in the order the Commission favours, so these are the ones to know first.

Directions · Directions : Time taken by the pipes to fill a tank/cistern

Study the following graph carefully to answer the given questions :

Time taken by the pipes to fill a tank/cistern (hours/minutes)

```chart:bar title: Time taken by the pipes to fill a tank/cistern (hours/minutes) unit: minutes series: INLET 1, INLET 2 A,B: 20, 10 C,D: 15, 20 E,F: 25, 20 G,H: 10, 4 I,J: 12, 18 K,L: 15, 30 M,N: 10, 12 ```

(For each pair of pipes, the first pipe is INLET 1 and the second pipe is INLET 2.)

1231.A large cistern can be filled by two pipes A and B. How many minutes will it take to fill the cistern from an empty state, if B is used for half the time and A and B fill it together for the other half ?#

Junior Auditor (Group B) 2024
  • A7.5 minutes
  • B2.5 minutes
  • C4.0 minutes
  • D8.0 minutes

1232.Two pipes G and H are used to fill a cistern. If they are opened on alternate minutes and if pipe G is opened first, in how many minutes will the tank be full ?#

Junior Auditor (Group B) 2024
  • A5 to 6 minutes
  • B3 to 4 minutes
  • C8 to 9 minutes
  • D6 to 7 minutes

1233.A tap A can fill a tank of 600 liters capacity in 30 minutes. Another tap B can fill the same tank in 40 minutes. If A and B together fill the tank in 30 minutes and at the same time some water get wasted due to leakage in the tap, then how much water get wasted every minute?#

Scientific Assistant (D.N.a) (Group B) 2023Scientific Officer (D.N.a) (Group B) 2023+1 more
  • A27 liters
  • B21.5 liters
  • C15 liters
  • DNone of these

1234.Two taps can fill a tank in 20 minutes and 30 minutes respectively. There is an outlet tap at exactly half level of that rectangular tank which can pump out 50 litres of water per minute. If the outlet tap is open, then it takes 24 minutes to fill an empty tank. What is the volume of the tank?#

Scientific Assistant (Polygraph) (Group B) 2023Scientific Officer (Polygraph) (Group B) 2023
  • A900 litres
  • B1500 litres
  • C1200 litres
  • D2400 litres

1235.Water flowing from a tap at a constant rate of r litres/minute can fill a cylindrical tank in 6 minutes. A hole is made at the bottom of the tank so that water flows out of the tank at a constant rate = one-third the rate of flow of water from the tap. When the tank gets full, the hole gets sealed automatically. If the tank (with the hole) is empty to begin with and water starts flowing from the tap at rate r litres/minute, how long will it take for the tank to become full ?#

Naib Tehsildar 2023
  • A8 minutes
  • B9 minutes
  • C12 minutes
  • D18 minutes

1236.Pipe A fills a tank of 700 litres capacity at the rate of 40 litres a minute. Another pipe B fills the same tank at the rate of 30 litres a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 litres a minute. If pipe A is kept open for a minute and then closed and pipe B is kept open for a minute and then closed and then pipe C is kept open for a minute and then closed and the cycle repeated, how long will it take for the empty tank to overflow ?#

Inspector, Cooperative Societies 2022
  • A42 minutes
  • B39 minutes
  • C40 minutes 33 seconds
  • DNone of the above

Solutions

6 answers · same numbers
1231.(D) 8.0 minutes

From the graph, A fills the cistern in 20 minutes and B in 10 minutes. Let the job take t minutes. B works throughout, and A joins only for the second half. > B alone for t/2 fills (t/2)(1/10) > A and B together for t/2 fill (t/2)(1/20 + 1/10) = (t/2)(3/20) > (t/2)(1/10 + 3/20) = 1 → (t/2)(1/4) = 1 → t = 8 The cistern fills in 8.0 minutes.

1232.(A) 5 to 6 minutes

From the graph, G fills the cistern in 10 minutes and H in 4 minutes. So in a minute G fills 1/10 of it and H 1/4. A pair of alternate minutes fills 1/10 + 1/4 = 7/20. > after 4 minutes: 2 × 7/20 = 7/10 filled > 5th minute (G): 7/10 + 1/10 = 4/5 filled > remaining 1/5 at H's rate = (1/5) ÷ (1/4) = 0.8 minute > total = 5.8 minutes So the tank is full between 5 and 6 minutes.

1233.(C) 15 liters

Tap A fills 600/30 = 20 litres a minute and tap B 600/40 = 15 litres a minute, so together they should supply 35 litres a minute. Since the tank still took 30 minutes, the net inflow was only 600/30 = 20 litres a minute. > wasted = 35 − 20 = 15 litres per minute The leak wastes 15 litres every minute.

1234.(A) 900 litres

Together the two taps fill 1/20 + 1/30 = 1/12 of the tank per minute. So without the outlet the tank fills in 12 minutes and the lower half in 6 minutes. The outlet sits at half level. So it drains 50 L/min only while the upper half is being filled. With the outlet open, the upper half takes 24 − 6 = 18 minutes. Let the volume be V litres. > Upper half: (V/12 − 50) × 18 = V/2 > 1.5V − 900 = 0.5V → V = 900 Or: the outlet removes 50 × 18 = 900 L. That equals the water the taps deliver in the extra 12 minutes, that is one full tank. The volume is 900 litres.

1235.(B) 9 minutes

The tap fills the tank in 6 minutes, so it fills 1/6 of the tank each minute. The hole empties one-third of that. > tap: 1/6 per minute > hole: 1/3 × 1/6 = 1/18 per minute > net: 1/6 − 1/18 = 3/18 − 1/18 = 2/18 = 1/9 per minute At 1/9 of the tank per minute, the tank fills in 9 minutes.

1236.(D) None of the above

One 3-minute cycle is A, then B, then the drain C. It adds 40 + 30 − 20 = 50 litres. > 13 cycles = 39 min → 650 L > minute 40 (A, +40) → 690 L > pipe B supplies the last 10 L at 30 L/min = 20 s The tank overflows at 40 minutes 20 seconds. That is not 39 min, 42 min or 40 min 33 s, so none of the listed times is right.

Common questions about Pipes & Cisterns in PPSC

How many Pipes & Cisterns questions come in PPSC exams?

The Commission set 6 Pipes & Cisterns questions across 8 papers between 2022–2024. That is the whole set, not a sample — every one of them is in the book, and the 6 most-asked are on this page free.

Are PPSC Pipes & Cisterns questions repeated?

Not in this set — each of these 6 was set once in the years covered. Questions elsewhere in the book do repeat, and carry a badge saying how often.

Where can I get Pipes & Cisterns MCQs with answers and solutions?

Here. Every question on this page is a solved MCQ: the four options as printed, the correct answer, and a worked explanation in plain English — not just a letter. The rest of the 6 are in the book, in the same form.

Can I practice these Pipes & Cisterns questions online?

Switch to Attempt mode at the top of the questions. You get one question at a time and it is marked the moment you pick an option, with the reason underneath — the same way the exam feels, on your phone.

Is a PDF available?

The questions are on screen rather than in a downloadable file, so they stay current and correct. The printed book has all 6 of these plus the rest of the Reasoning & Aptitude section, and every buyer gets the whole thing online as well.

Which papers asked Pipes & Cisterns

The exams behind these questions, most first. A paper here is a sitting: a question set in two papers of the same sitting counts once.

ExamYearQuestions
Junior Auditor (Group B)20242
Scientific Officer (Teaching) (Group B)20231
Scientific Officer (D.N.a) (Group B)20231
Scientific Assistant (D.N.a) (Group B)20231
Naib Tehsildar20231
Scientific Assistant (Polygraph) (Group B)20231
Scientific Officer (Polygraph) (Group B)20231
Inspector, Cooperative Societies20221

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