Question 1011852
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I'm a 66 year old man with a debate with my wife.  I say the mixture would be 4 to 1 she disagrees. 
A 40% solution is to be mixed with water how much water is needed to make the solution 10%?
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3 volumes of water per volume of 40% solution will give you 10% solution.


The wife is always right.


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This is why.


{{{(0.4V)/(V + W)}}} = 0.1.


V i the volume of your original 40% solution.
W is the volume of water to be added.

Solve it:

0.4V = 0.1V + 0.1W,

0.3V = 0.1W

{{{W/V}}} = {{{0.3/0.1}}} = 3.
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