Engineering Board Exam Reviewer · Mixture Problems · hard
A radiator holds 20 L of a 40% antifreeze solution. How many liters must be drained and replaced with pure antifreeze to obtain a 70% solution?
- 10 L
- 20 L
- 6 L
- 15 L
Answer
A. 10 L
Solution
Drain x L, then add x L of pure antifreeze (the volume stays 20 L): 0.40(20-x)+x=0.70(20) 8+0.6x=14 x=10 L.
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