SOLUTION: we wish to obtain a 40% solution of nitric acid by mixing a 20% solution and a 70% solution of the acid. what percentages of the final solution should be taken from the 20% and 70%

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Question 211083: we wish to obtain a 40% solution of nitric acid by mixing a 20% solution and a 70% solution of the acid. what percentages of the final solution should be taken from the 20% and 70% solutions?
thanks for the help

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
we wish to obtain a 40% solution of nitric acid by mixing a 20% solution and a 70% solution of the acid.
what percentages of the final solution should be taken from the 20% and 70% solutions
:
It does not give the amt of final solution to be made.
Assume it is 100 units, easy to change amt to per cent.
:
Let x = amt of 70% solution used
then
(100-x) = amt of 20% solution
:
A typical mixture equation;
.7x + .2(100 - x) = .4(100)
.7x + 20 - .2x = 40
.7x - .2x = 40 - 20
.5x = 20
x = 20%2F.5
x = 40 units of 70% solution
and
100 - 40 = 60 units of 20% solution
:
We can say we will take 40% from the 70% solution
and take 60% from the 20% solution