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A mixture of 40 liters of milk and water contains 10% water.

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munia123
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A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   Updated on: 04 Jul 2018, 06:18
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A mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

A. 4
B. 5
C. 6
D. 7
E. 8
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B

Originally posted by munia123 on 27 Oct 2010, 12:57.
Last edited by abhimahna on 04 Jul 2018, 06:18, edited 1 time in total.
Edited the question and added OA
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Bunuel
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   27 Oct 2010, 17:44
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munia123 wrote:
hey guys, i have got another problem. please help me to solve it.the problem says,

a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

my answer is 4 liter but, i am not sure. please help me.


Please read and follow: how-to-improve-the-forum-search-function-for-others-99451.html

So please:
Provide answer choices for PS questions.

Let the amount of water to be added be \(x\) liters.

We want the percentage of water to increase from 10% to 20% or percentage of non-water to decrease from 90% to 80%. Note that when we add \(x\) liters of water the amount of non-water in mixture in liters remains the same, so:

\(0.9*40=0.8(40+x)\) --> \(x=5\).

Or, the amount of water after adding \(x\) liters of water (\(0.2*(40+x)\)) should be equal to initial amount of water (\(0.1*40\)) plus the amount of water we add (\(x\))

\(0.2*(40+x)=0.1*40+x\) --> \(x=5\).

Hope it helps.
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schebro
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   27 Oct 2010, 13:33
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40 liters of mixture contains 4 liters of water (10%). So, it has 36 liters of milk.

if 36 liters <-> 80%,
100% <-> (36/80)x100 = 45 liters

So, the total water in the mixture should be 9 liters. Since there is already 4 liters in the mixture, 5 liters need to be added.
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   19 Apr 2014, 00:34
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No need to complicate much.

4 ltr - Water
36 ltr - milk

Let X water be added then the new mixture must have 20% water

Then

4 + X = 20/100 (40+X)

X=5
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   29 Sep 2014, 01:18
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Initial water = 4

Initial Solution = 40

Say Quantity "x" water added

Final water = 4+x

Final Solution = 40+x

\(\frac{4+x}{40+x} = \frac{20}{100} = \frac{1}{5}\)

x = 5

Answer = 5 (No OA for this question)
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   28 Oct 2010, 02:56
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vitamingmat wrote:
Bunuel wrote:
munia123 wrote:
hey guys, i have got another problem. please help me to solve it.the problem says,

a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

my answer is 4 liter but, i am not sure. please help me.


Please read and follow: how-to-improve-the-forum-search-function-for-others-99451.html

So please:
Provide answer choices for PS questions.

Let the amount of water to be added be \(x\) liters.

We want the percentage of water to increase from 10% to 20% or percentage of non-water to decrease from 90% to 80%. Note that when we add \(x\) liters of water the amount of non-water in mixture in liters remains the same, so:

\(0.9*40=0.8(40+x)\) --> \(x=5\).

Or, the amount of water after adding \(x\) liters of water (\(0.2*(40+x)\)) should be equal to initial amount of water (\(0.1*40\)) plus the amount of water we add (\(x\))

\(0.2*(40+x)=0.1*40+x\) --> \(x=5\).

Hope it helps.

Hi Bunuel, i got the different ans.. let me know where i m wrong....

Problem again :
a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

a mixture of 40 ltrs water + milk contains 10% of water so 4 ltrs are water rest 36 ltrs are milk.

if i want to make water 20% in the mixture
40*20% = (4+ x) here x is the water to be added to the mixture

so, i got x as 4

please suggest me if i gone wrong???


4+x liters of water is 20% of 40+x liters of mixture not 40.
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   28 Oct 2010, 02:42
Bunuel wrote:
munia123 wrote:
hey guys, i have got another problem. please help me to solve it.the problem says,

a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

my answer is 4 liter but, i am not sure. please help me.


Please read and follow: how-to-improve-the-forum-search-function-for-others-99451.html

So please:
Provide answer choices for PS questions.

Let the amount of water to be added be \(x\) liters.

We want the percentage of water to increase from 10% to 20% or percentage of non-water to decrease from 90% to 80%. Note that when we add \(x\) liters of water the amount of non-water in mixture in liters remains the same, so:

\(0.9*40=0.8(40+x)\) --> \(x=5\).

Or, the amount of water after adding \(x\) liters of water (\(0.2*(40+x)\)) should be equal to initial amount of water (\(0.1*40\)) plus the amount of water we add (\(x\))

\(0.2*(40+x)=0.1*40+x\) --> \(x=5\).

Hope it helps.




Hi Bunuel, i got the different ans.. let me know where i m wrong....

Problem again :
a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

a mixture of 40 ltrs water + milk contains 10% of water so 4 ltrs are water rest 36 ltrs are milk.

if i want to make water 20% in the mixture
40*20% = (4+ x) here x is the water to be added to the mixture

so, i got x as 4

please suggest me if i gone wrong???
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munia123
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   28 Oct 2010, 04:06
thanks to bunuel and also thanks to that person who asked the question to bunnel ( i also thought that 40*20% = 40+x). now i have understood. thanks .
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sugand
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   27 Sep 2014, 00:40
munia123 wrote:
hey guys, i have got another problem. please help me to solve it.the problem says,

a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

my answer is 4 liter but, i am not sure. please help me.




hi how would u solve this using the allegation method ?
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gracie
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   16 Apr 2017, 13:43
munia123 wrote:
hey guys, i have got another problem. please help me to solve it.the problem says,

a mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

my answer is 4 liter but, i am not sure. please help me.


let w=water to be added
.10*40+w=.20(40+w)
w=5 liters
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   23 Jun 2020, 21:24
Given 40L water/milk, with water = 10%
40*0.1 = 4

(40+x)*20% = 4+x
(40+x)/5 = 4+x
40+x = 20+5x
20=4x
x=5 ---> need to add 5L of water

Check
40+5= 45
45/5=9 --20%
4+5=9---good
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   03 Aug 2021, 06:23
10% water in 40lit
90% milk in 40lit
we need to mix 100% pure water to get 20% water content in mixture
100% 10%
20%
w1/w2=20-10/100-20
w1/40=10/80
w1=5lit of water needs to be added
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink] New post   14 Feb 2024, 05:20
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Re: A mixture of 40 liters of milk and water contains 10% water. [#permalink]
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