A mixture containing 22% of ethanol is mixed with another mixture containing a% of ethanol in the ratio 6 : 7. If the percentage of ethanol in the final mixture is 15%, find the value of a.
Show answer & explanation
Correct answer: C
Explanation
Given:
First mixture = 22%
Second mixture = a%
Ratio = 6 : 7
Final mixture = 15%
Formula:
Average of mixture = (C₁ × Q₁ + C₂ × Q₂) / (Q₁ + Q₂)
15 = (22 × 6 + a × 7) / (6 + 7)
15 = (132 + 7a) / 13
195 = 132 + 7a
7a = 63
a = 9%