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# How many gallons of water must be mixed with 1 gallon of a 15% salt so

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Intern
Joined: 19 Dec 2009
Posts: 33
How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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15 Oct 2010, 09:20
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68% (01:11) correct 32% (01:28) wrong based on 200 sessions

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How many gallons of water must be mixed with 1 gallon of a 15% salt solution to obtain a 10% salt solution?

A. 0.50
B. 0.67
C. 1.00
D. 1.50
E. 2.00
[Reveal] Spoiler: OA
Manager
Joined: 08 Sep 2010
Posts: 223
Location: India
WE 1: 6 Year, Telecom(GSM)
Re: How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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15 Oct 2010, 21:56
3
KUDOS
rtaha2412 wrote:
Does anyone have a good strategy to solving solutions problems?

Question

How many gallons of water must be mixed with 1 gallon of a 15% salt solution to obtain a 10% salt solution?

A 0.50
b 0.67
c 1.00
d 1.50
e. 2.00

you are having 1 gallon of a 15% salt solution means you are having (15/100)*1 gallon of salt.

Now consider you are using x gallons of water and making it to (x+1) gallon of solution.now the salt content(15/100) will be the 10% of total solution.
Hence (10/100)(x+1)=15/100

Solving we get x=0.5 gallon.Answer is A.

Consider KUDOS if it is helpful to u.Thanks.
Math Expert
Joined: 02 Sep 2009
Posts: 43348
Re: How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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29 Nov 2016, 06:16
rtaha2412 wrote:
How many gallons of water must be mixed with 1 gallon of a 15% salt solution to obtain a 10% salt solution?

A. 0.50
B. 0.67
C. 1.00
D. 1.50
E. 2.00

Since we are adding pure water then the amount of salt in both solutions will be the same, so 0.15*1=0.1*(1+x) --> x=0.5.

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Manager
Joined: 27 Aug 2014
Posts: 56
Concentration: Strategy, Technology
GMAT 1: 660 Q45 V35
GPA: 3.66
WE: Consulting (Consulting)
Re: How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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29 May 2017, 19:21
Since we are adding pure water

I got the equation

x + .85 = .9 (1 + x)

x - 1/1 of x i.e. only water being added.
.85 - .85 gallons of water
.9 = the resultant percentage of water + salt.

Solve for it to get .50 Gallons.
Director
Joined: 07 Dec 2014
Posts: 884
Re: How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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30 May 2017, 09:27
rtaha2412 wrote:
How many gallons of water must be mixed with 1 gallon of a 15% salt solution to obtain a 10% salt solution?

A. 0.50
B. 0.67
C. 1.00
D. 1.50
E. 2.00

let w=gallons of water to be mixed
.85+w=.9(1+w)
w=.5 gallons
VP
Joined: 22 May 2016
Posts: 1259
How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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02 Jun 2017, 15:46
rtaha2412 wrote:
How many gallons of water must be mixed with 1 gallon of a 15% salt solution to obtain a 10% salt solution?

A. 0.50
B. 0.67
C. 1.00
D. 1.50
E. 2.00

Let x = the number of gallons of water to be added

(concentration of A)*(Volume of A) + (concentration of B)* (Volume of B) = (desired concentration in resultant mixture)*(Volume of resultant mixture = A + B)

Water has a salt concentration of 0

(.15)*(1) + (0)(x) = (.10) (1 + x)

.15 = .10 + .10x

.05 = .10 x

$$\frac{.05}{.10}$$ = .50

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Formerly genxer123

Manager
Joined: 02 Feb 2016
Posts: 89
GMAT 1: 690 Q43 V41
Re: How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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17 Jun 2017, 02:27
How can this be solved by the mixture chart method?
BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 1815
Location: India
WE: Sales (Retail)
How many gallons of water must be mixed with 1 gallon of a 15% salt so [#permalink]

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17 Jun 2017, 02:58
2
KUDOS
TheMastermind wrote:
How can this be solved by the mixture chart method?

Since pure water contains 0% salt
the mixture chart will be as follows :

0(Pure water) - - - - - 15(Salt Solution)
- - - - - - - - - - - 10 - - - - - - - - - - - - -
5 - - - - - - - - - - - - - - - - - - - - - - - 10

This in in proportion 1 : 2
Since we are mixing 1 gallon of 15% salt solution, which is twice the portion of pure water,
we will be adding 0.5 gallon of pure water(Option A)

Hope this helps
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How many gallons of water must be mixed with 1 gallon of a 15% salt so   [#permalink] 17 Jun 2017, 02:58
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