Help on a problem on mixtures

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Help on a problem on mixtures

by praveen_gmat » Sat Jul 31, 2010 8:39 pm
There is a 40 litres solution of milk and water in which milk forms 72%. How much water must be added to this solution to make it a solution in which milk forms 60%?

How to solve? Pls help
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by outreach » Sat Jul 31, 2010 8:49 pm
11.2 - water
28.8 - milk
x - qty of water to be added
28.8/(40+x)=60/100
28.8/(40+x)=3/5
144=120+3x
x=8
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by indiantiger » Sun Aug 01, 2010 1:51 pm
First we need to find the amount of milk

72/100 * 40 = 28.8
amount of water = 40 -28.8 = 11.2

to get 60% milk by weight we need to add more water to increase water content in mixture
Let w be the additional water added
60/100 = 28.8 / 40 + w
6/10 = 28.8/40+w
288 = 240 + 6w
w = 8 lts (ANSWER)
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