SOLUTION: A car's radiator contains 12 L of antifreeze at a 25% concentration. How many liters must be drained and then replaced by pure antifreeze to bring the concentration to 50% 9the ma

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Question 68408This question is from textbook Basic technical mathematics with calculus
: A car's radiator contains 12 L of antifreeze at a 25% concentration. How many liters must be drained and then replaced by pure antifreeze to bring the concentration to 50% 9the manufactor's "safe" level)? This question is from textbook Basic technical mathematics with calculus

Answer by ptaylor(2198)   (Show Source): You can put this solution on YOUR website!
ALSO SEE PROBLEM #66436 FOR A SIMILAR PROBLEM
let x=amount of 25% solution that needs to be drained and replaced with pure antifreeze
Then 25-x is the amount of 25% antifreeze left after the system was drained
Now we know that the amount of pure antifreeze left after the system was drained .25(12-x),plus the amount of pure antifreeze added back in (x) equals the amount of pure antifreeze in the final solution (12)(.50). So our equation to solve is:
.25(12-x)+x=(12)(.50) simplifying, we get:
3-.25x+x=6 subtract 3 from both sides:
.75x=3
x=4 liters needs to be drained and replaced by pure antifreeze----ans
ck
.25(12-4)+4=6
2+4=6
6=6
Hope this helps ----ptaylor

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