Question

You need a 55% alcohol solution. On hand, you have a 525 mL of a 45% alcohol mixture. You also have 90% alcohol mixture. How much of the 90% mixture will you need to add to obtain the desired solution? You will need _____mL of the 90% solution to obtain _____mL of the desired 55% solution.

Answer 1

Let's call the amount of 90% solution x.

We can write:

45% * 525 + 90%x = 55%(x + 525)

0.45 * 525 + 0.9x = 0.55(x + 525)

Solving for x we get x = 150 so the first blank is 150 and the second blank is 525 + 150 = 675.