In 70 liters of a mixture of milk and water, the quantity of

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In 70 liters of a mixture of milk and water, the quantity of [#permalink]

24 Jan 2012, 14:40

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In 70 liters of a mixture of milk and water ,the quantity of water is 10%. how much water should be added so that new mixture may 25% water.

[Reveal] Spoiler:

can it solve through chemical mixture strategy in mgmat guide

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Re: mixture [#permalink]

24 Jan 2012, 14:51

TomB wrote:

In 70 liters of a mixture of milk and water ,the quantity of water is 10%. how much water should be added so that new mixture may 25% water.

[Reveal] Spoiler:

can it solve through chemical mixture strategy in mgmat guide

Please post answer choices for PS problems. Also make sure you don't reword the questions you post.

As for the question:
There are 10% of water in 70L --> there are 7L of waters;
After x liters of water is added amount of water becomes (7+x) liters, which on the other hand is 1/4th (25%) of new (70+x) liters of mixture: 7+x=1/4*(70+x) --> 28+4x=70+x --> x=14.

Hope it's clear.
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

25 Jan 2012, 02:16

70 = 0,1W + 0,9M
Water = 7 Liter

New1: Add x-Liter water to increase W% from 10% to 25%
New2:
7+x = (70+x)1/4
-42/4 = -3/4x
14 = x

You need to add 14 Liter of Water to get a total of 21 Liter of Water in 84Liter of mixture

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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

25 Jan 2012, 04:36

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TomB wrote:

In 70 liters of a mixture of milk and water ,the quantity of water is 10%. how much water should be added so that new mixture may 25% water.

[Reveal] Spoiler:

can it solve through chemical mixture strategy in mgmat guide

Check out how to handle generic mixture questions here:
http://www.veritasprep.com/blog/2011/04 ... -mixtures/

The formula discussed can be used in a ton of questions including this one. Once you get used to this method of solving, you will pretty much be solving this question orally. After going through the post, see if this makes sense:

Solution 1 has 10% water.
Solution 2 has 100% water. (You are mixing solution 1 with pure water.)
Mixture should have 25% water.
w1/w2 = (100 – 25)/(25 – 10) = 75/15 = 5/1
So volume of solution 1 : volume of water = 5:1
Solution 1 is 70 litres, so 14 litres of water must be added.
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

25 Jan 2012, 09:15

my way
now water is 7/70
it will be (7+X)/(70+X) and it shoud =1/4.
solve and get the answer

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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

25 Jan 2012, 11:43

first the amount of water was 70*10%=7

(7+x)/(70+x)=1/4
x=14
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

26 Jan 2012, 06:25

In 70 ltr solution we have 63 ltr of milk and 7 ltr of water
now we are adding water but the amount of milk remains constant so (70+x)*75/100 = 63 where x is the amount of water added
on solving x=14

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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

28 Feb 2012, 18:23

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I draw the solution for you (attached). It might help you understand it a bit easier.

Attachments

mixture.png [ 25.98 KiB | Viewed 1632 times ]

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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

29 Feb 2012, 13:18

(7+x)/(70+x)=1/4
Solve for x; x=14

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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

15 Apr 2012, 21:44

Karishma,

I found your post on mixtures very useful. I am stuck in the above problem. Please help
I solved w1/w2 to be
(90-25)/(25-10) = 65/15.

Can you please explain how you got 75/15?
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

17 Apr 2012, 11:44

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ENAFEX wrote:

Karishma,

I found your post on mixtures very useful. I am stuck in the above problem. Please help
I solved w1/w2 to be
(90-25)/(25-10) = 65/15.

Can you please explain how you got 75/15?

The two mixtures are: a 10% water solution, only water (which is 100% water)
We combine them to get 25% water solution.
Therefore, it is actually (100 - 25)/(25 - 10) and not (90 - 25)/(25 - 10)
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] 17 Apr 2012, 11:44

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In 70 liters of a mixture of milk and water, the quantity of

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