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# A 100-litre mixture of milk and water contains 36 litres of

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Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
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A 100-litre mixture of milk and water contains 36 litres of [#permalink]

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19 Nov 2017, 21:40
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alphonsa wrote:
A 100-litre mixture of milk and water contains 36 litres of milk. 'x' litres of this mixture is removed and replaced with an equal quantum of water. If the process is repeated once, then the concentration of the milk stands reduced at 25%. What is the value of x?

A) 17.5 litres
B) 16.67 litres
C) 17.67 litres
D) 16.5 litres
E) 16 litres

Source: 4Gmat

Responding to a pm:

First check this post: https://www.veritasprep.com/blog/2012/0 ... -mixtures/

You are removing a part of the solution and adding water. When you add water, the amount of milk remains the same.

C1*V1 = C2*V2
This is repeated once more.

C2 = C1 * (V1/V2)^2

$$.25 = .36 * [\frac{(100 - x)}{100}]^2$$

$$\frac{(100 - x)}{100} = \frac{5}{6}$$

x = 100/6 = 16.67 litres
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Re: A 100-litre mixture of milk and water contains 36 litres of [#permalink]

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20 Nov 2017, 16:18
VeritasPrepKarishma wrote:
alphonsa wrote:
A 100-litre mixture of milk and water contains 36 litres of milk. 'x' litres of this mixture is removed and replaced with an equal quantum of water. If the process is repeated once, then the concentration of the milk stands reduced at 25%. What is the value of x?

A) 17.5 litres
B) 16.67 litres
C) 17.67 litres
D) 16.5 litres
E) 16 litres

Source: 4Gmat

Responding to a pm:

First check this post: https://www.veritasprep.com/blog/2012/0 ... -mixtures/

You are removing a part of the solution and adding water. When you add water, the amount of milk remains the same.

C1*V1 = C2*V2
This is repeated once more.

C2 = C1 * (V1/V2)^2

$$.25 = .36 * [\frac{(100 - x)}{100}]^2$$

$$\frac{(100 - x)}{100} = \frac{5}{6}$$

x = 100/6 = 16.67 litres

many many thanks to you, mam
Re: A 100-litre mixture of milk and water contains 36 litres of   [#permalink] 20 Nov 2017, 16:18

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