A bottle of mineral water contains 16oz. of liquid with 4%

Question

A bottle of mineral water contains 16oz. of liquid with 4% calcium content. How many ounces of this liquid shoud be poured out and replaced with a 6% calcium solution to obtain a 4.5% calcium solution?

Answer 1

Let X = the unknown amount of solution to pour out and replace.

(16oz - X) = amount of calcium solution to be poured out

(0.04)(16oz - X) = amount of calcium solution to be poured out at 4% calcium content

0.06(X) = amount of calcium solution to be replaced back in the bottle

0.045(16oz) = the newly obtained 16oz, 4.5% calcium solution

Given the above information, we can now express the mixture problem

by using the following equation:

(0.04)(16oz - X) + 0.06(X) = 0.045(16oz)

0.64 -0.04X + 0.06X = 0.72

0.02X = 0.08

X = 4oz