Question

How many quarts of pure antifreeze must be added to 8 quarts of a 20% antifreeze solution to obtain a 30% antifreeze solution?

Answer 1

9514 1404 393

Answer:

  1.1 quarts

Step-by-step explanation:

Let x represent the amount to be added, in quarts. Then the amount of anti-freeze in the resulting solution is ...

  0.20(8) + 1.00(x) = 0.30(8 +x)

  0.70x = 0.10(8) . . . . . . subtract 0.20(8)+0.30(x)

  x = 8/7 . . . . . . . . . . . . . divide by the coefficient of x

  x ≈ 1.142857 ≈ 1.1

About 1.1 quarts of pure antifreeze must be added.