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2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respectively, Both are opened together but at the end of 5 minutes B is turned off. Total time taken to fill the cisten is
  • a)
    17 minutes
  • b)
    16 minutes
  • c)
    15 minutes
  • d)
    10 minutes
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respec...
25(1 - t/20 ) = 5
∴ t = 16 minutes
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Most Upvoted Answer
2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respec...
To solve this problem, we can use the concept of rates. Let's assume that the capacity of the cistern is 100 units (this is an arbitrary assumption, the actual capacity doesn't matter for the calculation).

- 'A' fills the cistern in 20 minutes, so its filling rate is 100/20 = 5 units per minute.
- 'B' fills the cistern in 25 minutes, so its filling rate is 100/25 = 4 units per minute.

When both pipes are opened together, their combined filling rate is 5 + 4 = 9 units per minute.

Now, let's calculate the amount of water filled in the first 5 minutes when both pipes are open:
- 'A' fills at a rate of 5 units per minute, so in 5 minutes it fills 5 * 5 = 25 units.
- 'B' fills at a rate of 4 units per minute, so in 5 minutes it fills 4 * 5 = 20 units.

Therefore, in the first 5 minutes, the total amount of water filled is 25 + 20 = 45 units.

After 5 minutes, pipe 'B' is turned off. Now, only pipe 'A' is filling the cistern at a rate of 5 units per minute.

To find the remaining time to fill the cistern, we can calculate the remaining capacity of the cistern and divide it by the filling rate of pipe 'A'.

The remaining capacity of the cistern is 100 - 45 = 55 units.

The time required to fill the cistern with pipe 'A' alone is 55 / 5 = 11 minutes.

Adding the initial 5 minutes, the total time taken to fill the cistern is 5 + 11 = 16 minutes.

Therefore, the correct answer is option 'B', 16 minutes.
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2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respectively, Both are opened together but at the end of 5 minutes B is turned off. Total time taken to fill the cisten isa)17 minutesb)16 minutesc)15 minutesd)10 minutesCorrect answer is option 'B'. Can you explain this answer?
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2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respectively, Both are opened together but at the end of 5 minutes B is turned off. Total time taken to fill the cisten isa)17 minutesb)16 minutesc)15 minutesd)10 minutesCorrect answer is option 'B'. Can you explain this answer? for Railways 2024 is part of Railways preparation. The Question and answers have been prepared according to the Railways exam syllabus. Information about 2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respectively, Both are opened together but at the end of 5 minutes B is turned off. Total time taken to fill the cisten isa)17 minutesb)16 minutesc)15 minutesd)10 minutesCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Railways 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 2 pipes A and B can fill a cistern in 20 minutes and 25 minutes respectively, Both are opened together but at the end of 5 minutes B is turned off. Total time taken to fill the cisten isa)17 minutesb)16 minutesc)15 minutesd)10 minutesCorrect answer is option 'B'. Can you explain this answer?.
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