Question 719731: how many quarts of water must be added to 5 qt of 80% antifreeze solution to make 50 % antifreeze solution .
In my attempt
let x = # of quarts of water
0.80(X)+0.8(5) =0.50 solution not sure if this is correct
my answer was 5.625 quarts water
thank you
Answer by jsmallt9(3758)   (Show Source):
You can put this solution on YOUR website! If we add x quarts of water to 5 quarts of the 80% solution, then we will end up with x + 5 quarts of our final solution. And this final solution is supposed to be 50% antifreeze. So an expression for the amount of antifreeze in the final solution would be:
0.50 * (x + 5) or 0.50x + 2.5
The quarts of water you add will contribute no antifreeze to the final mixture. So the antifreeze you start with, 0.80*5 = 4, will be the same amount of antifreeze you end up with in the mixture. So:
4 = 0.50x + 2.5
This is an equation which will give us the solution to this problem.
Subtracting 2.5:
1.5 = 0.50x
Dividing by 0.50 (or multiplying by 2) we get:
3 = x
So we add 3 quarts of water to the 5 quarts of 80% antifreeze to get 50% antifreeze.
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