Word Problem

Question

You need a 55% alcohol solution. On hand, you have a 275 mL of a 40% alcohol mixture. You also have 80% alcohol mixture. How much of the 80% mixture will you need to add to obtain the desired solution?

You will need

________mL of the 80% solution
to obtain

_________mL of the desired 55% solution.

Answer 1

Let x = mls of 80% solution

(x)(80%) + (275 ml)(40%) = (275 + x)(55%)

80x + 11,000 = 15,125 + 55x

25x = 4125

x = 165 mls of 80% 

Adding this to 275 ml of 40% gives 440 mls of desired 55%