Question

A lab assistant wants to make 5 liters of 27.2% acid solution. If solutions of 30% and 16% are in stock, how many liters of each must be mixed to prepare the solution?

Answer 1

Let x = 30% y=16%

We need 5 liters of 27.2% acid
A) x + y = 5
B) .30 x + .16y = 5 * .272
Multiplying A by -.30
A) -.30 x - .30y = -1.5 then adding to B
B) .30 x + .16y = 1.36
-.14y = -.14
y = 1 liter 16%
x = 4 liters 30%