A water tank is one – fifth full. Pipe A can fill a tank in 8 minutes and pipe B can empty it in 12 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?

Options
- 4.8 minute
- 7.6 minute
- 8.4 minute
- 10.4 minute

CORRECT ANSWER : 4.8 minute

Discussion Board
wrong solution

Pipe A fills faster than Pipe B empties, so the tank will be filled, not emptied.
Their net rate is
1
24
24
1
?
tank per minute, and 4/5 of the tank remains to be filled.
Therefore, the correct time is
4
5
×
24
=
19.2
5
4
?
×24=19.2 minute

harsha 07-6-2025 10:23 AM

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