Question

A Pharmacist whishes to mix a solution that is 6% Minoxidil. She has on hand 100 ml of 4% solution and wishes to add some 8% solution to obtain the desired 6% solution. How much 8% solution should she add?

Answer 1

She would need 100 ml of the 8% solution

Explanation:

You can always answer these questions using a proportion. The numerator will represent the amount of Minoxidil, and the denominator will represent the total amount of solution

She already ha 100 ml of a 4% solution. That means that she has 4 ml of Minoxidil already

`(4 + 0.08(S))/(100 + S) =(6)/(100)`

We can multiply both sides by 100 for simplicity

`(400 + 8S)/(100+S)=6\\ 400 + 8S =6(100 + S)\\400 + 8S = 600 + 6S\\2S = 200\\S = 100`