Question

A pharmacist is to prepare 15ml of special eye drops for a glaucoma patient. The eye drop solution have a 2% active ingredient, but the pharmacist has only 10% solution and 1 % solution in stock. How much of each type of solution must be used to fill the prescription?

Answer 1

The two solutions together should be 15 ml.So let there be x ml of 10% solution and y ml of 1% solution.
Now x+y=15
Also concentrations should match, so,
0.1x + 0.01y =.02*15
Solving the two simultaneous equations we get,
0.09x +0.15 =0.3
x=1.666ml of 10% solution and the rest is 1% solution