Quantitative Aptitude

Pipes and Cisterns

69 Questions

Pipes and cisterns problems test your understanding of inlet and outlet rates alongside time management. These questions are a staple in quantitative aptitude sections for SSC, banking, and railways. Mastering filling and emptying concepts is essential for scoring well.

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Pipes and Cisterns Questions

Multiple choice general knowledge math & puzzles

There are 900 bottles to be filled. Jim and Molly working independently but at the same time take 30 minutes to fill the bottles. How long should it take Molly working by herself to fill the bottles?

Statement 1 - Molly fills half as many bottles as Jim.

Statement 2 - Jim would take 45 minutes by himself.

Which of the statements above make it possible to answer the question.

  1. Statement 1 alone is sufficient, but statement 2 alone is not sufficient.

  2. Statement 2 alone is sufficient, but statement 1 alone is not sufficient.

  3. Both statements together are sufficient, but neither statement alone is sufficient.

  4. Each statement alone is sufficient
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To solve this question, you need to know how to set up a system of equations using the given information and how to solve for the unknown variable. Here is one possible explanation:

Let $x$ be the number of bottles that Jim fills in one minute and $y$ be the number of bottles that Molly fills in one minute. Then, we have the following equations:

  • $x + y = 30$ (the total number of bottles filled by Jim and Molly in one minute $\frac{900}{30}$)

Statement 1 tells us that $y = x/2$, which means that Molly fills half as many bottles as Jim in one minute. We can substitute this into the first equation and get:

  • $x + x/2 = 30$
  • $3x/2 = 30$
  • $x = 20$

This means that Jim fills 20 bottles in one minute and Molly fills 10 bottles in one minute. We can use this to find how long it takes Molly to fill the bottles by herself:

  • $30y = 900$
  • $30(10) = 900$
  • $y = 30$

So, Molly takes 30 minutes by herself to fill the bottles. Therefore, statement 1 alone is sufficient to answer the question.

Statement 2 tells us that $45x = 900$, which means that Jim would take 45 minutes by himself to fill the bottles. We can solve for x and get:

  • $x = 20$

This is the same as what we found from statement 1, so we can use it to find how long it takes Molly to fill the bottles by herself:

  • $y = x/2$
  • $y = 20/2$
  • $y = 10$

So, Molly fills 10 bottles in one minute and takes 30 minutes by herself to fill the bottles. Therefore, statement 2 alone is also sufficient to answer the question.

Since both statements alone are sufficient, the correct answer is D. Each statement alone is sufficient.

Multiple choice general knowledge

Pipe A can fill in 20 minutes and Pipe B in 30 mins and Pipe C can empty the same in 40 mins.If all of them work together, find the time taken to fill the tank

  1. 17 1/7 mins

  2. 20 mins

  3. 8 mins

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Combined rate = 1/20 + 1/30 - 1/40 = (6+4-3)/120 = 7/120 tank per minute. Time to fill = 120/7 = 17 1/7 minutes. Pipe A fills at 5% per minute, B at 3.33%, while C empties at 2.5% per minute, giving a net fill rate of about 5.83% per minute.

Multiple choice general knowledge math & puzzles

A pool has four taps. The first tap takes two days to fill the pool, the second tap three days, the third four days and the last one only 6 hours. How long will it take to fill the pool using all 4 taps at once? Round of answer to nearest High Minutes

  1. 3Hrs 43Mins

  2. 4Hrs 44Mins

  3. 3Hrs 44Mins

  4. 4Hrs 43Mins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calculating combined rates: Tap 1 = 1/2 pool per day, Tap 2 = 1/3 pool/day, Tap 3 = 1/4 pool/day, Tap 4 = 4 pools/day (since 6 hours = 0.25 days). Total rate = 0.5 + 0.333 + 0.25 + 4 = 5.083 pools/day. Time needed = 1/5.083 = 0.1966 days = 4.72 hours = 4 hours 43 minutes (rounded).

Multiple choice general knowledge math & puzzles

A tank has four pipes attached to it. The first one takes 60 hours to fill the tank, second one takes 80 hours to do the same, third one takes 40 hours to empty the tank and the fourth one takes 720 hours to empty the tank. Four taps are opened at the same time. How long will it take to fill the tank if the tank is half-filled before opening the taps?

  1. 7 Days and 12 Hours

  2. 7 Days and 10 Hours

  3. 7 Days and 11 Hours

  4. 7 Days and 13 Hours
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Combined rate: 1/60 + 1/80 - 1/40 - 1/720 = (12+9-18-1)/720 = 2/720 = 1/360 per hour. Half tank needs 0.5 tank at 1/360 rate = 180 hours = 7 days 12 hours. The fill pipes (1,2) together are faster than drain pipes (3,4), so net effect is filling.

Multiple choice general knowledge math & puzzles

A tank has four pipes attached to it. The first one takes 60 hours to fill the tank, second one takes 80 hours to do the same, third one takes 40 hours to empty the tank and the fourth one takes 720 hours to empty the tank. Four taps are opened at the same time. How long will it take to fill the tank if the tank is half-filled before opening the taps?

  1. 7 Days 10 Hours

  2. 7 Days 11 Hours

  3. 7 Days 12 Hours

  4. 7 Days 13 Hours
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Net rate per hour = (1/60 + 1/80 - 1/40 - 1/720) = (12+9-18-1)/720 = 2/720 = 1/360. To fill the remaining half (1/2), it takes 1/2 / 1/360 = 180 hours. 180 hours = 7 days and 12 hours.

Multiple choice general knowledge math & puzzles

A pool has four taps. The first tap takes two days to fill the pool, the second tap three days, the third four days and the last one only 6 hours. How long will it take to fill the pool using all 4 taps at once?

  1. 4 hours 43 minutes and 18 seconds.

  2. 4 hours 50 minutes and 17 seconds.

  3. 3 hours 43 minutes and 17 seconds.

  4. 4 hours 43 minutes and 17 seconds.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Convert all times to hours: Tap1=48h, Tap2=72h, Tap3=96h, Tap4=6h. Rates: 1/48, 1/72, 1/96, 1/6 pools per hour. Combined rate = 1/48+1/72+1/96+1/6 = 2/96+1.33/96+1/96+16/96 = 20.33/96 pools/hour. Time = 96/20.33 = 4.72h = 4h + 0.72*60min = 4h 43min + 0.2*60sec = 4h 43min 17sec.

Multiple choice general knowledge

Don't forget to turn the tap off properly after using. A dripping tap wastes 30 drops of water per minute and 380 litres (84 gallons) per month - this equates to 4,600 litres (1,008 gallons) per year

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A dripping tap wastes a surprising amount of water over time. The statistics given (30 drops per minute, 380 litres per month, 4,600 litres per year) are reasonable estimates. Always turn taps off fully and fix drips promptly.

Multiple choice general knowledge

Check for toilet tank leaks by adding food coloring to the tank. If the toilet is leaking, color will appear within 30 minutes. Check the toilet for worn out, corroded or bent parts. Most replacement parts are inexpensive, readily available and easily installed.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This describes a valid method to detect toilet tank leaks. Food coloring in the tank that appears in the bowl within 30 minutes indicates a leak. Fixing toilet leaks is an important water conservation measure, and replacement parts are typically inexpensive and easy to install.

Multiple choice general knowledge math & puzzles

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 2 hours to fill the tank with the large inlet pipe. On the other hand, it takes 4 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 6 hours. What fraction of the tank (initially empty) will be filled in 0.86 hours if all three pipes are in operation?

  1. 0.25

  2. 0.45

  3. 0.5

  4. 0.55

  5. 0.75
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Large inlet fills 1/2 tank per hour, small inlet fills 1/4 tank per hour, outlet empties 1/6 tank per hour. Net rate = 1/2 + 1/4 - 1/6 = 6/12 + 3/12 - 2/12 = 7/12 tank per hour. In 0.86 hours: 7/12 * 0.86 = 0.5017, approximately 0.5.

Multiple choice general knowledge math & puzzles

Pipe A can fill a tank in 20 min, Pipe B can fill a tank in 30 min. Pipe C can empty the tank in 40 min. If all of them work together, find the time taken to fill the tank.

  1. 20 min

  2. 17 1/7 min

  3. 14 min

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Combined rate = 1/20 + 1/30 - 1/40 = 6/120 + 4/120 - 3/120 = 7/120 tank per minute. Time = 120/7 = 17 1/7 minutes. This is a standard work rate problem with one outlet.

Multiple choice general knowledge math & puzzles

Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?

  1. 20 hrs

  2. 40 hrs

  3. 10 hrs

  4. 30 hrs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Both pipes fill the tank: A at 1/36 per hour and B at 1/45 per hour. Combined rate = 1/36 + 1/45 = (5+4)/180 = 9/180 = 1/20 per hour, so the tank fills in 20 hours. The other options do not match the combined rate.

Multiple choice general knowledge math & puzzles

Pipe A can fill a tank in 36 hours and pipe B can empty it in 45hours. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?

  1. 90 hrs

  2. 100 hrs

  3. 150 hrs

  4. 180 hrs
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pipe A fills at 1/36 of the tank per hour and pipe B empties at 1/45 per hour. The net fill rate is 1/36 - 1/45 = (5-4)/180 = 1/180 per hour, so the tank fills in 180 hours. Options 90, 100, and 150 hrs ignore the net rate.