Using 6 step method

Question

A pharmacist wishes to mix a solution that is 2% minoxidil. She has on hand 100 ml of a 1% solution and wishes to add some 4% solution to obtain the desired 2% solution. How much 4% solution should she add?

Answer 1

Too close to home here. Use these SOE to solve for the percentage of each mixture. Then go from there.

x+y=1

1x+4y=2

y=1-x

x+4(1-x)=2

x+4-4x=2

-3x=-2

x=2/3

y=1/3

Therefore x(1% solution) = 100ml is 2/3rds of the solution. Y (4% solution) is 1/3rd of the solution or 50 ml.

Check:

.666(1)+.333(4)=2