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# How many ounces of a 60% salt solution must be added to 50

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Manager
Joined: 10 Sep 2012
Posts: 137
How many ounces of a 60% salt solution must be added to 50  [#permalink]

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Updated on: 17 Dec 2012, 00:07
8
00:00

Difficulty:

5% (low)

Question Stats:

84% (01:28) correct 16% (01:51) wrong based on 302 sessions

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How many ounces of a 60% salt solution must be added to 50 ounces of a 20 percent salt solution so that the resulting mixture is 40% salt?

A. 16.67
B. 30
C. 50
D. 60.33
E. 70

I have the algebraic solution in front of me (and will post if anyone cares)

But I was wondering if there was a more intuitive, easy or plugging in way of solving this.

Originally posted by anon1 on 17 Dec 2012, 00:03.
Last edited by Bunuel on 17 Dec 2012, 00:07, edited 1 time in total.
Edited the question and tags.
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Joined: 02 Sep 2009
Posts: 54376
Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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17 Dec 2012, 00:10
1
anon1 wrote:
How many ounces of a 60% salt solution must be added to 50 ounces of a 20 percent salt solution so that the resulting mixture is 40% salt?

A. 16.67
B. 30
C. 50
D. 60.33
E. 70

I have the algebraic solution in front of me (and will post if anyone cares)

But I was wondering if there was a more intuitive, easy or plugging in way of solving this.

For 60% salt solution (X) and 20% salt solution (Y) to give 40%=(60+20)/2 salt solution, we should mix equal amounts of X and Y.

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Manager
Joined: 10 Sep 2012
Posts: 137
Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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17 Dec 2012, 00:15
Wow, that was pcretty eassy...

Bunuel, a couple of questions. #1 what if the numbers had not been perfectly in the middle like that?

What if the prompt had asked for a solution of 32% salt?

(would this even ever happen on the GMAT?)

And #2 , how were you able to recognize that? Are you just a genius like that or was there something in particular that caught your eye, either in regards to recognizing patterns or the nature of GMAT questions.?
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Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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19 Feb 2013, 23:59
2
We can do this by alligation method as well

60 20

40

60 - 40 = 20 & 40 - 20 = 20
; 20:20 = 1:1... it should be mixed in equal amounts ie. 50 ounces
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Manager
Joined: 03 Jan 2015
Posts: 59
Concentration: Strategy, Marketing
WE: Research (Pharmaceuticals and Biotech)
Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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12 Jan 2015, 16:24
1
Assume original solution = 100 oz @60% concentration:
Amount of salt = 60 oz

In 50 oz solution @ 20% concentration:
Amount of salt = 10 oz

Assume, we need 100 oz @ 40% concentration:
Let X = Amount of 60 oz solution we need for mixing.

Therefore, the equation is:
10 oz + 60X oz = 40 oz
X = 0.5 i.e. 50% or half of the solution

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Joined: 07 Dec 2014
Posts: 1179
Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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31 Jul 2016, 17:41
let x=ounces of 60% salt solution to be added
.2*50+.6x=.4(50+x)
x=50
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Re: How many ounces of a 60% salt solution must be added to 50  [#permalink]

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05 Sep 2017, 10:46
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Re: How many ounces of a 60% salt solution must be added to 50   [#permalink] 05 Sep 2017, 10:46
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