Problem Statement
A vessel contains 60 L of 25% salt solution. 12 L is drawn off and replaced with water. After repeating once more, what is the concentration of salt?
Explanation
Use dilution factor. Each time, fraction kept is 1 − 12/60 = 0.8. After two steps, salt amount is initial salt times 0.8 squared. Initial salt is 0.25×60 = 15 L. Final salt is 15×0.64 = 9.6 L. Concentration is 9.6 / 60 = 0.16? Wait volume stays 60, yes. But replacement with water keeps total 60 each time. After two steps salt is 9.6 L, so 9.6/60 = 0.16 or 16%. Correct answer is 16%.
Code Solution
SolutionRead Only
salt = 15×(1−12/60)^2 = 15×0.64 = 9.6 ⇒ % = 9.6/60=16%
