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m and n are both positive. Pump A pumps n liters of water

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m and n are both positive. Pump A pumps n liters of water

by M7MBA » Sun Feb 18, 2018 4:49 am
m and n are both positive. Pump A pumps n liters of water per minute, and pump B pumps m liters of water per minute. Is m < n ?

(1) x is the number of minutes it takes pump B to fill a 100 liter container alone, and 3x is the number of minutes it takes pump B to fill a 100 liter container while pump A pumps water out of that container.

(2) It takes (3x/2) minutes for pump A to fill a 100 liter container alone.

The OA is the option A.

Any expert may explain to me how to show that statement (1) is sufficient? I'm really confused here.
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Source: — Data Sufficiency |
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by DavidG@VeritasPrep » Tue Feb 20, 2018 11:08 am
M7MBA wrote:m and n are both positive. Pump A pumps n liters of water per minute, and pump B pumps m liters of water per minute. Is m < n ?

(1) x is the number of minutes it takes pump B to fill a 100 liter container alone, and 3x is the number of minutes it takes pump B to fill a 100 liter container while pump A pumps water out of that container.

(2) It takes (3x/2) minutes for pump A to fill a 100 liter container alone.

The OA is the option A.

Any expert may explain to me how to show that statement (1) is sufficient? I'm really confused here.
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Statement 1: No need to do any math here. Use a little logic. If B is pumping water into a container while A is pumping water out of the container, in order for that container to ever be filled, B has to be faster. Otherwise, A would empty out everything B pumps in! So the fact that the container fills means B must be faster than A. Sufficient.

Statement 2: Nothing about pump B. No Good.

The answer is A
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