SOLUTION: 12. A nurse wants to make 50 ml of a 12% salt solution. How many milliliters each of a 15% salt solution and a 10% salt solution should be mixed to produce the desired solution?

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Question 1158234: 12. A nurse wants to make 50 ml of a 12% salt solution. How many milliliters each of a 15% salt solution and a 10% salt solution should be mixed to produce the desired solution?
Found 3 solutions by josmiceli, josgarithmetic, greenestamps:
Answer by josmiceli(19441)   (Show Source):
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Let = ml of 15% solution needed
Let = ml of 10% solution needed
----------------------------------------------
(1)
(2)
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(2)
(2)
(2)
Multiply both sides of (1) by
and subtract (1) from (2)
(2)
(1)
------------------------------

and
(1)
(1)
--------------------
20 ml of 15% solution
30 ml of 10% solution
---------------------------
check:
(2)
(2)
(2)
(2)
(2)
OK

Answer by josgarithmetic(39630)   (Show Source):
You can put this solution on YOUR website!
v of the 15%
50-v of the 10%

-

.
.
.

Answer by greenestamps(13209)   (Show Source):
You can put this solution on YOUR website!

The two algebraic solutions you have received are valid, but a lot of work.

If an algebraic solution is not required, here is by far the easiest way to solve this kind of mixture problem.

The percentages of the two ingredients and the mixture are 10, 12, and 15. Here is the easy two-step solution.

(1) 12% is 2/5 of the way from 10% to 15%.
(2) Therefore, 2/5 of the mixture is the 15% salt solution.

ANSWER: The mixture needs to be 2/5 of 50 ml, or 20ml, of the 15% salt solution and 30 ml of the 10% salt solution.

CHECK:
20(.15)+30(.10) = 3+3 = 6
50(.12) = 6