How many ounces of a 10 % alcohol solution must be mixed with 18 ounces of a 15 % alcohol solution to make a 12 % alcohol solution?

27oz

Explanation:

Let the volume quantity of the 10% solution = x

The volume quantity of the 15% alcohol solution is known as = 18oz

Therefore the volume of the 12% product = 18oz + x

Therefore

0.10 * x + 0.15 * 18oz = 0.12 * (18oz+x)

0.15*18oz - 0.12*18oz = 0.12*x - 0.10*x

.

0.03*18oz = 0.02x

Dividing both sides by 0.02

x = 27oz

Verifying the answer, we have

0.1 * 27 + 18 * 0.15 = 0.12 * 45

2.7 + 2.7 = 5.4