Question

How many quarts of pure antifreeze must be added to 5 quarts of a 20​% antifreeze solution to obtain a 30​% antifreeze​ solution?

Answer 1

Answer:

5/7 quart

Step-by-step explanation:

Amount = concentration × volume

Amounts added = final amount

100% × x + 20% × 5 = 30% × (x+5)

Solving for x:

1.00x + 0.2×5 = 0.3×(x+5)

x + 1 = 0.3x + 1.5

0.7x = 0.5

x = 5/7

x ≈ 0.7

You should add 5/7 quart of pure antifreeze, or about 0.7 quart.