In a chemistry class, 12 L of a 12% alcohol solution must be mixed with a 20% solution to obtain a 14% solution. How many liters of the 20 % solution are needed?
Let ‘x’ litres of 20% solution is required
Now, Total quantity of final solution = (12+x) litres
Alcoholic content in the final solution = sum of the alcoholic content in the two mixing solutions
or, 14*(12+x)/100 = [1212/100] + [20x/100]
or, x = 4
Thus, 4 litres of 20% solution is required