Question

Ronald has a 10% solution of the fertilizer Super Grow. How much pure Super Grow should he add to the mixture to get 36 oz of a 12.5% concentration?

Answer 1

1 oz

Explanation:

Given that:

% solution of super grow fertilizer = 10%

To obtain mixture of 36oz of a 12.5% concentration

Let oz of pure supergrowth to be added = s

(Initial % * (36 - s) + s) / 36 = target concentration

(10% * (36 - s) + s) / 36 = 12.5%

(0.1(36 - s) + s) / 36 = 0.125

Cross multiply:

0.1(36 - s) + s =. 0.125 * 36

3.6 - 0.1s + s = 4.5

3.6 + 0.9s = 4.5

0.9s = 4.5 - 3.6

0.9s = 0.9

s =. 0.9/0.9

s = 1

Hence, 1 oz of pure supergrowth should be added to the 10% solution to get 36 oz of a 12.5% concentration.