Question

Jasmine wants to make a 30% alcohol solution. Shehas already poured 3 fluid ounces of a 72% alcoholsolution into a beaker. How many fluid ounces of a 9%alcohol solution must she add to create this desiredmixture?a

Answer 1

Let:

a = ounces of 72% alcohol solution

b = ounces 9% alcohol solution

c = ounces Final mixture:

so:

$\begin{gathered} 0.72a+0.09b=0.3(c) \\ where \\ a=3 \\ c=a+b=3+b \\ 3\cdot0.72+0.09b=0.3(3+b) \\ 2.16+0.09b=0.9+0.3b \\ 2.16-0.9=0.3b-0.09b \\ 1.26=0.21b \\ b=\frac{1.26}{0.21} \\ b=6 \end{gathered}$

She needs to add 6 oz of 9% alcohol solution to create the desired mixture