Math problem

Question

One canned juice drink is 20% orange juice; another is 5% orange juice. How many liters of each should by mixed together in order to get 15L that is 11% orange juice

Answer 1

Let x = volume of 5% orange juice, then 15L - x = volume of 20% orange juice

Let's convert the % figures to decimals, so 5% = 0.05, 11% = 0.11, and 20% = 0.2

 

So, our equation becomes 0.05x + 0.2(15L - x) = 15L • 0.11

expanding, we get 0.05x + 3L - 0.2x = 1.65L

combining, we get -0.15x = -1.35L; we multiply both sides by -1 to get

0.15x = 1.35L

Solving, x = 9L of 5% orange juice; then we need 6L of 20% orange juice

 

Proof: 9.0L • 0.05 + 6L • 0.2 = 15L •  0.11; 1.65L = 1.65L