Question

How many quarts of pure antifreeze must be added to 2 quarts of a 30 % antifreeze solution to obtain a 40 % antifreeze solution ?

( blank )quart ( s ) of pure antifreeze must be added

( Round to the nearest tenth as needed )

Answer 1

x = 2

Explanation:

To obtain a 40% antifreeze solution, we need to add more antifreeze to the 30% solution. Let's call the amount of pure antifreeze that needs to be added x. Then, the amount of antifreeze in the solution will be 2 + x quarts.

The concentration of antifreeze in the solution will be:

(0.30 * 2) + (0.100 * x) = 0.40 * (2 + x)

Solving for x:

0.60 + 0.100x = 0.40 * (2 + x)

Expanding the right-hand side:

0.60 + 0.100x = 0.80 + 0.40x

Solving for x:

0.100x = 0.20

x = 2

So, 2 quarts of pure antifreeze must be added to obtain a 40% antifreeze solution.