Answer:
67.5 litres of 12% alcohol and 37.5 litres of 20% alcohol
Step-by-step explanation:
To solve this question, the principle of going by average is needed, that is the average of both initial Alcohol solution is what is needed to get the exact alcohol solution being demanded in the question.
Let the litres of 12% to be mixed be denoted as xlitres
This means the liters of 20% to be mixed will be denoted as (100 - x) litres
Hence to get the exact 100 litres of 15%, we go by the Formula
[12 * x] + [20 * (100 - x)] = 100 * 15.
12x + 2000 - 20x = 1500
-8x + 2000 = 1500
2000 - 1500 = 8x
500 = 8x
x = 500/x
x= 62.5 Litres
100 - 62.5 = 37.5 Litres.
This means the mixture of 62.5 lites of 12% of alcohol and 37.5 litres Of 20% alcohol will give exactly 100litres of 15% alcohol.
