SOLUTION: You need a 40%saline solution for an experiment, but only have 25% saline and 75% saline solutions. How much of each would you have to combine to create 50ml of 40% saline solutio

Question 184451: You need a 40%saline solution for an experiment, but only have 25% saline and 75% saline solutions. How much of each would you have to combine to create 50ml of 40% saline solution?
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(48558) (Show Source):
You can put this solution on YOUR website!
You need a 40%saline solution for an experiment, but only have 25% saline and 75% saline solutions. How much of each would you have to combine to create 50ml of 40% saline solution?
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Equation:
salt + salt = salt
0.25x + 0.75(50-x) = 0.40*50
Multiply thru by 100 to get:
25x + 75*50 - 75x = 40*50
-50x = -35*50
x = 35mL (amt. of 25% solution in the mixture)
50-x = 15mL (amt. of 75% solution in the mixture)
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Cheers
Stan H.

Answer by josmiceli(6786) (Show Source):
You can put this solution on YOUR website!
Let = ml of 25% solution needed
Let = ml of 75% solution needed
In words:
((salt in 25% solution) + (salt in 75% solution)) / (total amount of solution) =
40%
given:
salt in 25% solution = ml
salt in 75% solution = ml
Total amount of solution = ml
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(1)
(2)
(2)
Multiply both sides of (1) by
(1)
Subtract (1) from (2)
(2)
(1)
(3)
(3)
and
(1)
(1)

35 ml of 25% solution and 15 ml of 75% solution are needed
check:
(2)
(2)
(2)
(2)
(2)
OK