Equal volumes of water were poured into 3 empty flasks

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swerve: Legendary Member; Posts: 2499; Joined: Sun Oct 29, 2017 2:04 pm; Followed by:6 members

Equal volumes of water were poured into 3 empty flasks

by swerve » Fri May 18, 2018 10:07 am

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Equal volumes of water were poured into 3 empty flasks, making one flask 1/6 full, one flask 1/8 full, and one flask 1/12 full. If half of the water from each of the two smallest flasks is then poured into the largest flask, what fraction of the largest flask will be filled with water?

A. 1/6
B. 1/4
C. 1/3
D. 3/8
E. 1/2

The OA is A.

Please, can anyone explain this PS question? I tried to solve it but I can't get the correct answer. I need help. Thanks

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Source: Beat The GMAT — Problem Solving | Fri May 18, 2018 10:07 am

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by [email protected] » Fri May 18, 2018 10:14 am

Hi swerve,

We're told that EQUAL volumes of water were poured into 3 empty flasks, making one flask 1/6 full, one flask 1/8 full, and one flask 1/12 full. Then, half of the water from each of the two smallest flasks is then poured into the largest flask. We're asked what fraction of the largest flask will be filled with water. This question can be solved by TESTing VALUES...

IF... 2 ounces are poured into EACH flask, then the total volume of each flask would be....
1st flash = 1/6 full = 12 ounces when full
2nd flash = 1/8 full = 16 ounces when full
3rd flash = 1/12 full = 24 ounces when full

When HALF of each of the water from the each of the two SMALLER flasks (that would be 1 ounce of water from EACH) is poured into the largest flask, then the largest flask will hold 2+1+1 = 4 ounces of water. Since that flask holds 24 ounces when FULL, it would now hold 4/24 = 1/6 of its capacity.

Final Answer: A

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Rich

Contact Rich at [email protected]

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Tue May 22, 2018 5:19 pm

swerve wrote:Equal volumes of water were poured into 3 empty flasks, making one flask 1/6 full, one flask 1/8 full, and one flask 1/12 full. If half of the water from each of the two smallest flasks is then poured into the largest flask, what fraction of the largest flask will be filled with water?

A. 1/6
B. 1/4
C. 1/3
D. 3/8
E. 1/2

We can assume that 2 ounces of water are poured into each of the flasks. Thus, the full capacities of the flasks are 12 oz, 16 oz, and 24 oz, respectively.
If half of the water from each of the two smallest flasks is then poured into the largest (24 oz) flask, then the largest flask will have 2 + 1 + 1 = 4 ounces of water and thus it will be
4/24 = 1/6 full.

Alternate Solution:

There were equal amounts of water in all the flasks and since half the water from the two smaller flasks is poured into the largest flask, the amount of the water in the largest flask will double. Since the largest flask is the one that was 1/12 full (which is because the same amount of water filled the least fraction of the flask); after the water is doubled, it will be 2 x 1/12 = 1/6 full.

Answer: A

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