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

100

Explanation:

Let x be the amount to be added of the second solution. For every 100ml of it 8 units of minoxidil are added. The total amount of solution will be (100 + x), so the final concentration is given by:

`4 / (100 + x) + 0.08x / (100 + x) = 0.06` [Multiplying by (100 + x)]

`4 + 0.08x = 6 + 0.06x` [Transposing terms]

`0.08x - 0.06x = 6 - 4` [ operating]

`0.02x = 2` [Dividing by 0.02]

`x=100`