Quantitative Aptitude

Pipes and Cisterns

535 Questions
All Delayed opening or closing 106 Combined pipes and the LCM shortcut 77 Find unknown pipe time 64 Efficiency ratios and faster-pipe relations 61 Flow rates based on pipe diameter 50 Leaks and reverse-rate questions 50 Actual capacity and pump-rate equations 44 Partial filling or emptying condition 44 Alternating pipes and changing phases 39

Pipes and Cisterns Questions

Multiple choice

Two pipes can fill a cistern separately in 24 min and 40 minute respectively. Waste pipe is opened which can drain the cistern at 30 liters/minute. If all the pipe are opened together then the cistern fills in one hour. The capacity (in litre) of the cistern is? दो पाइप क्रमशः 24 मिनट और 40 मिनट में अलग-2 एक कुंड को भर सकते हैं। अपशिष्ट पाइप खोला जाता है, जो 30 लीटर / मिनट की दर से पानी की निकासी कर सकता है। यदि सभी पाइप एक साथ खोले जाते हैं तो एक घंटे में कुंड भर जाता है। कुंड की क्षमता (लीटर में) है?

  1. 800

  2. 400

  3. 600

  4. 650

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let C be the capacity. Pipe 1 fills at C/24 per minute, Pipe 2 at C/40 per minute, waste pipe drains at 30 L/min. All together: C/24 + C/40 - 30 = C/60. Solving: C(1/24 + 1/40 - 1/60) = 30 gives C(6/120) = 30, so C = 600 liters. Option C is correct.

Multiple choice

Pipe A can fill a tank in 12 hrs, pipe B can fill in 15 hrs where as pipe C can fill in 20 hrs. Ramesh woke up at 6 AM and turned pipe B on ,he again came at 9:30 AM and turned A on and finally at 11:30 AM turned C also on. At what time tank will be completely filled? पाइप A 12 घंटे में एक टैंक भर सकता है, पाइप B 15 घंटे में भर सकता है, जबकि पाइप C 20 घंटे में टैंक भर सकता है। रमेश सुबह 6 बजे उठा और पाइप B को चालू कर दिया, वह फिर 9:30 बजे उठा और पाइप A को चालू कर दिया और आखिरकार 11:30 बजे उसने C को भी चालू कर दिया किस समय टैंक पूरी तरह से भर जाएगा?

  1. 1:05 PM

  2. 1:50 PM

  3. 2:20 PM

  4. 1:48 PM

  5. None of these इनमे से कोई नहीं
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pipe rates: A = 1/12 per hr, B = 1/15 per hr, C = 1/20 per hr. B runs 6:00-11:30 = 5.5 hrs → fills 5.5/15 = 11/30. A runs 9:30-11:30 = 2 hrs → fills 2/12 = 1/6 = 5/30. C runs from 11:30. After 11:30, all three work together at rate (1/12+1/15+1/20) = (5+4+3)/60 = 12/60 = 1/5 per hr. Remaining = 1 - (11/30 + 5/30) = 14/30 = 7/15. Time needed = (7/15) / (1/5) = 7/3 = 2.33 hrs = 2 hr 20 min. End time = 11:30 + 2:20 = 13:50 = 1:50 PM. Option B is correct.

Multiple choice

Two pipes can fill a cistern in 3 hours and 4 hours respectively and a waste pipe can empty it in 2 hours. If all the three pipes are kept open, then the cistern will be filled in

  1. 5 hours

  2. 8 hours

  3. 10 hours

  4. 12 hours
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fill rates: 1/3 and 1/4 per hour. Empty rate: 1/2 per hour. Net rate = 1/3 + 1/4 - 1/2 = (4+3-6)/12 = 1/12. So cistern fills in 12 hours. Option C (10 hours) is a distractor - possibly from averaging the fill rates without proper calculation.

Multiple choice

A cistern can be filled by a tap in 17.5 hrs while it can be emptied by another tap in 42 hrs. If both pipes are opened simultaneously, then after how much time will the cistern get filled? (in hours) एक टंकी को 17.5 घंटे में एक नल द्वारा भरा जा सकता है जबकि इसे 42 घंटे में दूसरे नल से खाली किया जा सकता है। यदि दोनों पाइप एक साथ खोले जाते हैं, तो टंकी कितने समय के बाद भर जाएगी ? (घंटे में)

  1. 24घंटे

  2. 25घंटे

  3. 30घंटे

  4. 45घंटे

  5. None of these इनमें से कोई नहीं
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fill rate = 1/17.5 per hr, Empty rate = 1/42 per hr. Net rate = 1/17.5 - 1/42 = (42 - 17.5)/(17.5*42) = 24.5/735 = 1/30. Time to fill = 1/(1/30) = 30 hours.

Multiple choice

A cistern is filled by 3 pipes A, B and C with uniform flow. The second pipe B takes3/2 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. एक टंकी में 3 पाइप A, B और C एकसमान प्रवाह से भरे हुए हैं। दूसरा पाइप B, A द्वारा टैंक को भरने में लिए गए समय का 3/2 गुना समय लेता है, जबकि C, B द्वारा टैंक को भरने में लिए गए समय का दोगुना समय लेता है। यदि तीनों पाइप टैंक को 7 घंटे में भर सकते हैं, तो अकेले पाइप A द्वारा टैंक को भरने में लगने वाला समय ज्ञात कीजिए।

  1. 12

  2. 13

  3. 14

  4. 15

  5. 16
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let pipe A take x hours to fill the tank alone. Then pipe B takes (3/2)x hours, and pipe C takes 2 × (3/2)x = 3x hours. Their rates are: A = 1/x, B = 2/(3x), C = 1/(3x) per hour. Combined rate: 1/x + 2/(3x) + 1/(3x) = 1/x + 3/(3x) = 1/x + 1/x = 2/x. Together they take 7 hours, so (2/x) × 7 = 1 (tank filled). Therefore 14/x = 1, giving x = 14 hours.

Multiple choice

Which information are necessary to answer the questions asked- Pipe D is opened for first 6 minutes then closed and pipe C is opened. Find the time taken by pipe C to fill the remaining part of the tank. पाइप D पहले 6 मिनट के लिए खोला है फिर बंद कर दिया जाता है और पाइप C खोला जाता है। टैंक के बचे हुए हिस्से को भरने के लिए पाइप C द्वारा लिया गया समय ज्ञात कीजिये। (I). Pipe A and pipe B together can fill a tank in 15 minutes. (II). Pipe A, Pipe B and Pipe D they can fill the tank in 12 minutes. (III). Pipe C and pipe D together can fill the tank in 10 minutes. (I) पाइप A और पाइप B एक साथ 15 मिनट में एक भर सकते हैं। (II) पाइप A, पाइप B और पाइप D 12 मिनट में टैंक भर सकते हैं। (III) पाइप C और पाइप D एक साथ 10 मिनट में टैंक भर सकते हैं।

  1. All I, II and III सभी I, II तथा III

  2. Only II and III केवल II तथा III

  3. Only II केवल II

  4. Any two of the three तीनों में से कोई भी दो

  5. Even I, II and III together are not sufficient. I, II तथा III भी एक साथ पर्याप्त नहीं हैं
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

We need pipe C's time to fill remaining tank. From I, II, III: Let A+B rate = 1/15, A+B+D = 1/12, so D = 1/12 - 1/15 = 1/60 (60 days). C+D = 1/10, so C = 1/10 - 1/60 = 5/60 = 1/20 (20 days). Pipe D fills 6/60 = 10% in 6 min. Remaining 90% by C: (9/10) ÷ (1/20) = 18 minutes. All three statements are needed.

Multiple choice

Pipe 'A' can fill a tank in 18 hours and pipe 'B' can fill in 30 hours. Both the pipes opened together but after 5 hours pipe 'B' closed. In how many hours will pipe 'A' take to fill the remaining part of tank.

  1. 15 hr

  2. 18 hr

  3. 10 hr

  4. 12 hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pipe A fills 1/18 of tank per hour; Pipe B fills 1/30 per hour. Combined rate = 1/18 + 1/30 = 5/90 + 3/90 = 8/90 per hour. In 5 hours together: 5 × 8/90 = 40/90 = 4/9 filled. Remaining tank = 1 - 4/9 = 5/9. Pipe A alone fills at 1/18 per hour. Time needed = (5/9) ÷ (1/18) = (5/9) × 18 = 5 × 2 = 10 hours. Option C is correct.

Multiple choice

In the following questions, two quantities are given as Quantity I and Quantity II. Find the correct relationship among them. Quantity I: Three pipes P, Q and R are attached to a tank. Pipe P alone and Pipe Q alone can fill the tank in 30 hours and 20 hours respectively. If pipe P opened for 10 hours and closed, then pipe Q opened for 5 hours and closed and pipe R alone can fill the remaining tank in 5 hours. How many time pipe R alone take to fill the whole tank? Quantity II: Three pipes A, B and C can fill a tank in 10 hours. After working at it together for 3 hours, C is closed and A and B can fill the remaining part in 14 hours. How much time taken by C to fill the tank alone? निम्नलिखित प्रश्नों में, दो मात्राएँ मात्रा I और मात्रा II के रूप में दी गई हैं। इन मात्राओं के बीच सही सम्बन्ध ज्ञात कीजिये। मात्रा I: एक टंकी से तीन पाइप P, Q और R संलग्न हैं । पाइप P अकेले और पाइप Q अकेले 30 घंटे और 20 घंटे में क्रमशः टैंक भर सकते हैं। यदि पाइप P 10 घंटे के लिए खोला गया और फिर बंद कर दिया गया, उसके बाद पाइप Q 5 घंटे के लिए खोला गया और फिर बंद कर दिया गया और पाइप R अकेले 5 घंटे में शेष टैंक को भर सकता है। पूरे टैंक को भरने के लिए अकेले R कितना समय लेगा? मात्रा II: तीन पाइप A, B और C 10 घंटे में एक टंकी भर सकते हैं। 3 घंटे के लिए एक साथ काम करने के बाद, C बंद कर दिया जाता है और A और B शेष भाग को 14 घंटों में भर सकते है। अकेले C टैंक भरने के लिए कितना समय लेगा?

  1. Quantity I > Quantity II मात्रा I > मात्रा II

  2. Quantity I > Quantity II मात्रा I ≥ मात्रा II

  3. Quantity II > Quant
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Quantity I: P fills 1/3 in 10h, Q fills 1/4 in 5h, remaining 5/12 filled by R in 5h, so R alone takes 6h. Quantity II: Combined rate 1/10, after 3h only 7/10 left for A+B who fill it in 14h, giving C alone 30h. So Quantity II > Quantity I.

Multiple choice

Two different pump A and B filling a tank together. Pump A fill the tank through a pipe which diameter 7 cm and rate of flow of water is 10 cm/sec. Another Pump B fill the tank through a pipe which diameter 8.4 cm and rate of flow of water is 50 cm/sec. If the capacity of the tank is 9471 liter then in how many hours the tank will be full filled?

  1. 20 minutes

  2. 30 minutes

  3. 40 minutes

  4. 36 minutes

  5. None of these
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Pump A flow rate = π × (3.5)² × 10 = 122.5π cm³/sec. Pump B flow rate = π × (4.2)² × 50 = 882π cm³/sec. Combined flow = 1004.5π cm³/sec. Tank capacity = 9471 liters = 9,471,000 cm³. Time = 9,471,000/(1004.5π) ≈ 2999 seconds ≈ 50 minutes. None of the given options (20, 30, 36, 40 minutes) match this answer.

Multiple choice

Three pipes P , Q , R can separately fill a cistern in 4 , 8 and 12 hours respectively. Another pipe S can empty the completely filled cistern in 10 hours. Which of the following arrangements will fill the empty cistern in less time than others?

  1. Q alone

  2. P and S are open

  3. P, R and S are open

  4. P, Q and S are open
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Rates: P = 1/4, Q = 1/8, R = 1/12 (fill), S = -1/10 (empty). Option A: Q alone = 1/8, time = 8 hours. Option B: P + S = 1/4 - 1/10 = 3/20, time = 20/3 = 6.67 hours. Option C: P + R + S = 1/4 + 1/12 - 1/10 = 1/5, time = 5 hours. Option D: P + Q + S = 1/4 + 1/8 - 1/10 = 9/40, time = 40/9 = 4.44 hours. Option D is fastest.

Multiple choice

Pipes A and B can fill a tank in 12 minutes and 15 minutes, respectively. The tank when full can be emptied by pipe C in x minutes. When all the three pipes are opened simultaneously, the tank is full in 10 minutes. The value of x is:

  1. 24

  2. 36

  3. 20

  4. 28
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pipes A and B fill at rates 1/12 and 1/15 per minute respectively. Together they fill at 1/12 + 1/15 = 9/60 = 3/20 per minute. Pipe C empties at 1/x per minute. Net rate with all three = 3/20 - 1/x = 1/10 (since tank fills in 10 minutes). Solving: 3/20 - 1/10 = 1/x, so 1/x = 1/20, giving x = 20 minutes. The emptying pipe partially offsets the filling pipes.

Multiple choice

Three pipes A, B, C are attached to a tank respectively. Pipe A, B are filling pipes that can fill the tank in 45 and 54 minutes while C can empty the tank in 72 Minutes. Pipe A, C are opened for 30 minutes then they are closed, Pipe B and C are opened for 24 minutes then they are closed. After that, all three pipes were opened for the whole time. Find the time taken by all pipes to fill the remaining tank?
  1. $\(\frac{680}{29}\)$
  2. $\(\frac{690}{31}\)$
  3. $\(\frac{690}{29}\)$
  4. $\(\frac{680}{31}\)$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

First 30 min: A and C together fill (1/45 - 1/72) × 30 = 1/4 of tank. Next 24 min: B and C together fill (1/54 - 1/72) × 24 = 1/9 of tank. Total filled = 13/36, so 23/36 remains. All three together fill at rate 1/45 + 1/54 - 1/72 = 29/1080 per minute. Time needed = (23/36) ÷ (29/1080) = 690/29 minutes.

Multiple choice

If pipe E can drain out the water from a small pond in 35 hours while another pipe F takes 21 hours to drain water out of same small pond completely. If both pipes together can drain 40 litres per hour together, find the capacity of the tank. (In metre)

  1. 500

  2. 525

  3. 625

  4. 600
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Combined rate = 40 L/hr. Individual rates: E = C/35, F = C/21. So C/35 + C/21 = 40. LCM(35,21) = 105. 3C + 5C = 40×105 = 4200. 8C = 4200; C = 525. Answer is in litres, question asks for metres but likely means litres.

Multiple choice

Pipes A and B can fill a tank in 16 hours and 24 hours, respectively, whereas pipe C can empty the full tank in 40 hours. All three pipes are opened together, but pipe A is closed after 10 hours. After how many hours will the remaining part of the tank be filled?

  1. 10

  2. 20

  3. 12.5

  4. 15.5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Combined rate when all three open: (1/16 + 1/24 - 1/40) = (15/120 + 5/120 - 3/120) = 17/120 tank/hour. In 10 hours: 10 × 17/120 = 17/12 = 1 5/12 tank filled (tank overflows). But A closes at 10h. After 10h: 17/12 - 10/16 = 17/12 - 5/8 = (34-15)/24 = 19/24 tank filled. Remaining: 5/24. Rate after A closes: (1/24 - 1/40) = (5/120 - 3/120) = 2/120 = 1/60. Time needed: (5/24) ÷ (1/60) = (5/24) × 60 = 12.5 hours. Options A, B, D are incorrect.

Multiple choice

A large pipe has the capacity to fill a cistern in 8 hours. Four smaller pipes, with one-fourth the efficiency as that of larger pipe, are attached to the cistern. Find the ratio of time taken by each small pipe to fill a cistern to the time taken by larger pipe to fill the cistern alone?

  1. 4:1

  2. 2:5

  3. 1:4

  4. 1:3

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The large pipe fills the cistern in 8 hours. A small pipe with 1/4 efficiency will take 4 times longer = 32 hours. The ratio of small pipe time to large pipe time is 32:8 = 4:1.