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23 Mar 2026, 19:00
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D
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Difficulty:
25%
(medium)
Question Stats:
72% (01:30) correct
28%
(01:55)
wrong
based on 71
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A drain pump can remove water from a storage tank at a constant rate of n liters per hour, while an inlet valve can add water to the tank at a constant rate of m liters per hour, where n > m. If both start operating at the same time when the tank contains exactly 168 liters of water, how many hours will it take for the tank to become empty?
(1) n - m = 24
(2) After 3 hours of both operating, the tank contains 96 liters of water.
(1) n - m = 24
(2) After 3 hours of both operating, the tank contains 96 liters of water.
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28 Mar 2026, 03:45
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GMAT Club Official Solution:
A drain pump can remove water from a storage tank at a constant rate of n liters per hour, while an inlet valve can add water to the tank at a constant rate of m liters per hour, where n > m. If both start operating at the same time when the tank contains exactly 168 liters of water, how many hours will it take for the tank to become empty?
Time to empty the tank = (initial amount of water)/(net draining rate) = 168/(n - m).
(1) n - m = 24
So time = 168/24 = 7 hours. Sufficient.
(2) After 3 hours of both operating, the tank contains 96 liters of water.
In 3 hours, the tank goes from 168 to 96, a drop of 72 liters. So the net draining rate is 72/3 = 24 liters per hour, meaning n - m = 24. Then time = 168/24 = 7 hours. Sufficient.
Answer: D
A drain pump can remove water from a storage tank at a constant rate of n liters per hour, while an inlet valve can add water to the tank at a constant rate of m liters per hour, where n > m. If both start operating at the same time when the tank contains exactly 168 liters of water, how many hours will it take for the tank to become empty?
Time to empty the tank = (initial amount of water)/(net draining rate) = 168/(n - m).
(1) n - m = 24
So time = 168/24 = 7 hours. Sufficient.
(2) After 3 hours of both operating, the tank contains 96 liters of water.
In 3 hours, the tank goes from 168 to 96, a drop of 72 liters. So the net draining rate is 72/3 = 24 liters per hour, meaning n - m = 24. Then time = 168/24 = 7 hours. Sufficient.
Answer: D
General Discussion
23 Mar 2026, 23:59
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One is having a rate of n
Other is having m.
Each our they drain n-m
Hence total time = 168/n-m
Statement 1:
Clearly SUFFICIENT.
Statement 2:
Rate of drainage mentioned so the same ratio will carry on till it becomes completely empty as well.
SUFFICIENT.
Answer: Option D
Other is having m.
Each our they drain n-m
Hence total time = 168/n-m
Statement 1:
Clearly SUFFICIENT.
Statement 2:
Rate of drainage mentioned so the same ratio will carry on till it becomes completely empty as well.
SUFFICIENT.
Answer: Option D
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