Question 1180854

You need a 95% alcohol solution. On hand, you have a 15 mL of a 10% alcohol mixture. How much pure alcohol will you need to add to obtain the desired solution?

You will need
 (?) mL of pure alcohol
to obtain
(?) mL of the desired 95% solution.
<pre>Let amount of pure alcohol, be A
Then we get: .1(15) + A = .95(15 + A)
.1(15) + A = .95(15) + .95A
A - .95A = .95(15) - .1(15)
.05A = .85(15)
Amount of pure alcohol to mix, or {{{highlight_green(matrix(1,6, A, "=", .85(15)/.05, "=", 255, mL))}}}