Question

7) (Extra Credit) A chemist needs to mix a 12 % solution with a 20% solution to obtain 180 ounces of a 15% solution. How many ounces of each of the solutions must be used? 12%________ 20%__________

Answer 1

Explanation:

Let x be the amount of 12%

Let y be the amount of 20%

x + y = 180

x = 180 - y

x(0.12) + y(0.20) = 180(0.15)

(180 - y)(0.12) + y(0.20) = 27

(180)(0.12) - 0.12y + 0.20y = 27

21.6 + 0.08y = 27

0.08y = 5.4

y = 67.5 oz of 20% solution

x = 180 - 67.5 = 112.5 oz of 12% solution