SOLUTION: How many liters of a 15% saline solution must be added to 8 liters of a 4% saline solution to produce a 7% solution? note: Do NOT solve the entire problem. Answer only part (a) and

Algebra ->  Equations -> SOLUTION: How many liters of a 15% saline solution must be added to 8 liters of a 4% saline solution to produce a 7% solution? note: Do NOT solve the entire problem. Answer only part (a) and      Log On


   

Question 1092435: How many liters of a 15% saline solution must be added to 8 liters of a 4% saline solution to produce a 7% solution? note: Do NOT solve the entire problem. Answer only part (a) and part (b) below.
A)In solving this problem, what would you assume as a variable?
B)Find the amount of pure saline that  is present in 8 liters of 4% saline solution?
FOR A I GOT 1) x = number of liters in 15% saline solution
FOR B I GOT amount of pure saline present in 8 liters of 4% saline solution = 0.04* 8 = 0.32 liters
IS THIS CORRECT?

Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the volume, liters, of the 15% saline to add.

The amount of dissolved material in the 8 liters of 4% might be represented as 8%2A%280.04%29, ...
-
If percent concentration is as weight per volume, then
%284%2F100%29%28grams%2Fmilliliters%29
and
8%2A1000%2Amilliliters%2A%284%2F100%29%2A%28grams%2Fmilliliters%29=80%2Agrams


To solve the problem presented,
%2815x%2B4%2A8%29%2F%28x%2B8%29=7

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!

I see you got two previous responses to your question. In the first, the focus was to chastise you for using the term "pure saline"; in the second, the focus of the response was on changing liters to grams. And in the second response, you were shown an equation you could use to solve the problem -- even though you specifically asked not to be. And the equation was shown with no explanation; so it would not have been any help if you needed help actually setting up and solving the problem.

But neither response answered your two specific questions....

So, for A, as long as you mean
x = number of liters OF 15% saline solution
(instead of number of liters IN 15% saline solution)
then yes, that would be the most logical choice for a variable, since it is exactly what the problem asks you to find.

And your calculation for part B is fine.