Question

how many quarts of pure antifreeze must be added to 8 quarts of a 20% antifreeze solution to obtain a 50% antifreeze solution?

Answer 1

4.8 qt

Explanation:

Let x = volume (in quarts) of pure antifreeze.

Let y = volume (in quarts) of 20% antifreeze solution.

Amount of antifreeze in solution:

x + 0.2y = 0.5(x + y)

y = 8

x + 0.2 × 8 = 0.5(x + 8)

x + 1.6 = 0.5x + 4

0.5x = 2.4

x = 4.8

Answer: 4.8 qt