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# Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa

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Math Expert
Joined: 02 Sep 2009
Posts: 58427
Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa  [#permalink]

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16 Apr 2018, 05:16
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Difficulty:

35% (medium)

Question Stats:

65% (01:31) correct 35% (01:27) wrong based on 208 sessions

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Bill has 20 kilograms of a 20% salt solution. How many kilograms of salt should he add to make it a 25% salt solution?

A. 1
B. 5/4
C. 4/3
D. 4
E. 5

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Joined: 03 Mar 2018
Posts: 30
GMAT 1: 620 Q44 V31
Re: Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa  [#permalink]

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16 Apr 2018, 05:28
1
Bunuel wrote:
Bill has 20 kilograms of a 20% salt solution. How many kilograms of salt should he add to make it a 25% salt solution?

A. 1
B. 5/4
C. 4/3
D. 4
E. 5

20% of 20 Kg solution is salt - 4kg

let x kg salt be added to make it 25%

4+x / 20+x = 0.25
4+x = 0.25(20+x)
4+x = 5+0.25x
x-0.25x = 5-4
0.75x = 1
(3/4)x = 1
x=4/3

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Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa  [#permalink]

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22 Apr 2018, 18:30
Bunuel wrote:
Bill has 20 kilograms of a 20% salt solution. How many kilograms of salt should he add to make it a 25% salt solution?

A. 1
B. 5/4
C. 4/3
D. 4
E. 5

Let $$x$$ = amount, in kg, of 100% salt to be added
$$A$$ = solution with 20% salt
$$x$$ is 100% salt = decimal value of 1

One weighted average formula you can use (in which the percent sign = concentration of salt):

(% A)(Vol A) + (% x)(amt. x) = (% of A+x)(Vol A+x)

$$.20(20) + 1(x) = .25(20 + x)$$
$$4 + x = 5 + .25x$$
$$.75x = 1$$
$$x = \frac{1}{.75}=\frac{1}{(\frac{3}{4})}=(1*\frac{4}{3})=\frac{4}{3}$$

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Re: Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa  [#permalink]

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31 Jan 2019, 18:41
Bunuel wrote:
Bill has 20 kilograms of a 20% salt solution. How many kilograms of salt should he add to make it a 25% salt solution?

A. 1
B. 5/4
C. 4/3
D. 4
E. 5

We have a 20 kilogram solution that is 4 kg of salt. We can let n = the additional salt needed to make the solution 25% salt and create the equation:

(4 + n)/(20 + n) = 1/4

4(4 + n) = 20 + n

16 + 4n = 20 + n

3n = 4

n = 4/3

Alternate Solution:

To 20 kg of 20% salt he will add x kg of 100% salt to get (20 + x) kg of 25% salt. We can convert this to an equation:

20*0.20 + x*1.0 = (20 + x)(0.25)

4 + x = 5 + 0.25x

0.75x = 1

75x = 100

x = 4/3

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Re: Bill has 20 kilograms of a 20% salt solution. How many kilograms of sa   [#permalink] 31 Jan 2019, 18:41
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