Mixture Problem

Question

A nurse needs to create as much of a 10% concentration of saline from a stock supply of 8 pints of 5% and unlimited 30% solutions. How much of the 30% solution should she add to the 8 pints of 5% to make as much 10% solution as possible?

Answer 1

8(.05) + x(.30) = y(.10)

let x + 8 = y

Substitute:

.40 + .30x = (x + 8)(.10)

.40 + .30x = .10x + .80

.20x = .40

x = 2 pints of 30%

y = 10 pints total