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- List the given numbers and units.
- Choose the formula that matches the asked value.
- Simplify carefully and compare with options.
Correct Answer: B
Correct Answer: B
Method / Topic: Pipes and Cisterns
The answer follows from the arithmetic relation between the given values.
Short Explanation
Detailed Explanation
Correct Answer: B
Method / Topic: Pipes and Cisterns
Treat the complete tank as one unit of work. Convert each filling time into a filling rate and each outlet or leak time into an emptying rate. Add inlet rates, subtract outlet or leak rates, and then calculate the required time or fraction.
Combined rate = 1/20 + 1/30 = 1/12. Time = 12 minutes.
CHECK:
The resulting rate, time, or fraction corresponds to the selected
Do not add an outlet or leak as positive work. Also distinguish carefully between the fraction filled and the fraction remaining empty.
PRACTICAL EXAMPLE:
If one pipe adds water while another removes water simultaneously, the net filling rate is the filling rate minus the emptying rate.
Therefore, the correct
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Learn + Solve: Shortcut, Trap & Fast Route Click to view shortcut, steps, and common mistake
Shortcut used, common trap, and the fastest solving route
- List the given numbers and units.
- Choose the formula that matches the asked value.
- Simplify carefully and compare with options.
Two pipes can fill a cistern in 20 minutes and 30 minutes respectively. How long will they take together?
Explanation
Correct Answer: B
Method / Topic: Pipes and Cisterns
The answer follows from the arithmetic relation between the given values.
Short Explanation
Detailed Explanation
Correct Answer: B
Method / Topic: Pipes and Cisterns
Treat the complete tank as one unit of work. Convert each filling time into a filling rate and each outlet or leak time into an emptying rate. Add inlet rates, subtract outlet or leak rates, and then calculate the required time or fraction.
Combined rate = 1/20 + 1/30 = 1/12. Time = 12 minutes.
CHECK:
The resulting rate, time, or fraction corresponds to the selected
Do not add an outlet or leak as positive work. Also distinguish carefully between the fraction filled and the fraction remaining empty.
PRACTICAL EXAMPLE:
If one pipe adds water while another removes water simultaneously, the net filling rate is the filling rate minus the emptying rate.
Therefore, the correct
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