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15 Dec 2014, 02:58
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
80% (01:48) correct
20%
(02:06)
wrong
based on 411
sessions
History
Date
Time
Result
Not Attempted Yet
Five gallons of a solution of vinegar and water with 8% vinegar is to be diluted with water to make a 4% vinegar mixture. How many gallons of water should be added?
A. 10
B. 5
C. 4
D. 2
E. 1
Source: Bell Curves
A. 10
B. 5
C. 4
D. 2
E. 1
Source: Bell Curves
15 Dec 2014, 04:33
Kudos
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Its been given that there is 5 gallons of water and Vinegar with 8% of vinegar.
ie 8% of vinegar in 5 gallons is (8/100)*5 = 0.4 gallons of Vinegar and 4.6 gallons of water.
To make it 4% how many gallons of water should be added to the existing solution(5 g)
let us say it is x. i.e current Vinegar solution/(current soln in gallons + water to be added)=0.04
>> 0.4/(5+x)=4%
0.4/(5+x)=0.04 >> 5+x= 0.4/0.04=10
>>x=5
Ans B
ie 8% of vinegar in 5 gallons is (8/100)*5 = 0.4 gallons of Vinegar and 4.6 gallons of water.
To make it 4% how many gallons of water should be added to the existing solution(5 g)
let us say it is x. i.e current Vinegar solution/(current soln in gallons + water to be added)=0.04
>> 0.4/(5+x)=4%
0.4/(5+x)=0.04 >> 5+x= 0.4/0.04=10
>>x=5
Ans B
General Discussion
23 Dec 2014, 11:32
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Hi rvc27,
In these types of mixture questions, if the answers are numbers, then it's likely that you can TEST THE ANSWERS to quickly get to the solution. Here's how:
First, we need to know about the original mixture of vinegar and water. We're told that a 5 gallon mixture is 8% vinegar....
(5 gallons)(.08) = 0.4 gallons vinegar
The rest = 4.6 gallons water
We're told to ADD WATER until the mixture goes from 8% vinegar to 4% vinegar.
Since the answer choices are numbers, we know that one of them will lead us to a 4% mix when added to the current mix. Changing 8% to 4% means that we have to add a significant amount of water (relative to what we started with), so I would TEST one of the bigger numbers first.
Let's TEST B
If 5 gallons of water were added, then we'd have....
0.4 gallons vinegar
9.6 gallons of water
0.4/10 = 4% vinegar. This is EXACTLY what we're looking for, so B MUST be the answer.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
In these types of mixture questions, if the answers are numbers, then it's likely that you can TEST THE ANSWERS to quickly get to the solution. Here's how:
First, we need to know about the original mixture of vinegar and water. We're told that a 5 gallon mixture is 8% vinegar....
(5 gallons)(.08) = 0.4 gallons vinegar
The rest = 4.6 gallons water
We're told to ADD WATER until the mixture goes from 8% vinegar to 4% vinegar.
Since the answer choices are numbers, we know that one of them will lead us to a 4% mix when added to the current mix. Changing 8% to 4% means that we have to add a significant amount of water (relative to what we started with), so I would TEST one of the bigger numbers first.
Let's TEST B
If 5 gallons of water were added, then we'd have....
0.4 gallons vinegar
9.6 gallons of water
0.4/10 = 4% vinegar. This is EXACTLY what we're looking for, so B MUST be the answer.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
