Question
Download Solution PDFPipe A can fill a tank in 9 minutes, while pipe B can empty the completely filled tank in 10 minutes. Initially, pipe A is opened and after 3 minutes pipe B is also opened. In how much time (in minutes) will the remaining tank be filled completely?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
Pipe A fills tank in = 9 min
Pipe B empties tank in = 10 min
Pipe A is opened first, and B is opened after 3 min
Calculation:
Assume total capacity of tank = LCM of 9 and 10 = 90 units
Work rate of A = 90 ÷ 9 = 10 units/min (filling)
Work rate of B = 90 ÷ 10 = 9 units/min (emptying)
First 3 minutes: Only A works → Work done = 3 × 10 = 30 units
Remaining = 90 − 30 = 60 units
Now A and B both work together:
Net work per minute = 10 − 9 = 1 unit/min
Time to fill remaining 60 units = 60 ÷ 1 = 60 minutes
Total time to fill the remaining tank = 60 minutes
∴ The correct answer is 60 minutes.
Last updated on Jul 21, 2025
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