Final answer:
The percent of fruit juice in Brand A is 10%, calculated by setting up an equation based on the total concentration of fruit juice in the mixture and solving for Brand A's concentration.
Step-by-step explanation:
To find the percent of fruit juice in Brand A if the mixture of 8 L of Brand A and 4 L of Brand B contained 20% fruit juice, with Brand B containing 40% fruit juice, we can set up an equation based on the concentration of fruit juice in the total mixture.
Let the percent of fruit juice in Brand A be x. The total volume of the fruit drink is 8 L of Brand A plus 4 L of Brand B, which is 12 L. Since Brand B contains 40% fruit juice, the volume of fruit juice in Brand B is 0.40 * 4 L = 1.6 L.
The total amount of fruit juice in the mixture is 20% of 12 L, which is 2.4 L. The equation to represent the mixture is:
8L * (x / 100) + 1.6 L = 2.4 L
This simplifies to:
8x + 160 = 240
We can then solve for x:
8x = 240 - 160
8x = 80
x = 10
Therefore, the percent of fruit juice in Brand A is 10%.