In 70 liters of a mixture of milk and water, the quantity of : GMAT Problem Solving (PS)
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# 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]

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24 Jan 2012, 13:40
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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:
14

can it solve through chemical mixture strategy in mgmat guide
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24 Jan 2012, 13:51
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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:
14

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]

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25 Jan 2012, 01:16
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]

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25 Jan 2012, 03:36
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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:
14

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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Get started with Veritas Prep GMAT On Demand for $199 Veritas Prep Reviews Manager Joined: 12 Nov 2011 Posts: 143 Followers: 0 Kudos [?]: 22 [1] , given: 24 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 25 Jan 2012, 08:15 1 This post received KUDOS my way now water is 7/70 it will be (7+X)/(70+X) and it shoud =1/4. solve and get the answer Senior Manager Joined: 23 Oct 2010 Posts: 386 Location: Azerbaijan Concentration: Finance Schools: HEC '15 (A) GMAT 1: 690 Q47 V38 Followers: 21 Kudos [?]: 322 [0], given: 73 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 25 Jan 2012, 10:43 first the amount of water was 70*10%=7 (7+x)/(70+x)=1/4 x=14 _________________ Happy are those who dream dreams and are ready to pay the price to make them come true I am still on all gmat forums. msg me if you want to ask me smth Manager Status: MBA Aspirant Joined: 12 Jun 2010 Posts: 178 Location: India Concentration: Finance, International Business WE: Information Technology (Investment Banking) Followers: 3 Kudos [?]: 79 [0], given: 1 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 26 Jan 2012, 05:25 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 Intern Joined: 30 Nov 2011 Posts: 7 Followers: 0 Kudos [?]: 5 [3] , given: 1 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 28 Feb 2012, 17:23 3 This post received KUDOS I draw the solution for you (attached). It might help you understand it a bit easier. Attachments mixture.png [ 25.98 KiB | Viewed 5007 times ] Intern Joined: 24 Feb 2012 Posts: 33 Followers: 0 Kudos [?]: 15 [0], given: 18 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 29 Feb 2012, 12:18 (7+x)/(70+x)=1/4 Solve for x; x=14 Manager Status: And the Prep starts again... Joined: 03 Aug 2010 Posts: 138 Followers: 2 Kudos [?]: 47 [0], given: 20 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 15 Apr 2012, 20:44 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? _________________ My First Blog on my GMAT Journey Arise, Awake and Stop not till the goal is reached Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 7118 Location: Pune, India Followers: 2128 Kudos [?]: 13618 [1] , given: 222 Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink] ### Show Tags 17 Apr 2012, 10:44 1 This post received KUDOS Expert's post 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) _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

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13 Oct 2013, 14:55
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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19 Oct 2013, 22:46
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:
14

can it solve through chemical mixture strategy in mgmat guide

@banuel or @veritasprepkarishma please can you modify this problem to include ans choices.
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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20 Oct 2013, 03:11
ankur1901 wrote:
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:
14

can it solve through chemical mixture strategy in mgmat guide

@banuel or @veritasprepkarishma please can you modify this problem to include ans choices.

No answer choices are available for this question.
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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15 Dec 2014, 04:27
VeritasPrepKarishma, How can we come to know which problems can be solved using the weighted averages formula..Is it applicable to all mixture problems?Or specific ones?
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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15 Dec 2014, 18:59
Ralphcuisak wrote:
VeritasPrepKarishma, How can we come to know which problems can be solved using the weighted averages formula..Is it applicable to all mixture problems?Or specific ones?

For most mixture problems, weighted average formula is quite convenient. Whenever you add two things and consider the final solution or have the final solution and split it into two, weighted averages formula is relevant. For some replacement problems, you need additional theory discussed here: http://www.veritasprep.com/blog/2012/01 ... -mixtures/
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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16 Dec 2014, 00:14
Thank you for the response Karishma..Will look into the article and implement it for mixture problems..
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Re: In 70 liters of a mixture of milk and water, the quantity of [#permalink]

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20 Mar 2016, 01:46
Hello from the GMAT Club BumpBot!

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Re: In 70 liters of a mixture of milk and water, the quantity of   [#permalink] 20 Mar 2016, 01:46
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