Question

A scientist needs 10 liters of a 20% acid solution for an experiment, but she has only a 5% solution and a 40% solution. To the nearest tenth of a liter, about how many liters of the 5% and the 40% solutions should she mix to get the solution she needs? Write and solve an equation to match the situation.

Answer 1

see below

Explanation:

Acid in = acid out acid out = 10 liters of 20% = .2 * 10 = 2

x = 5% amount

10-x = 40% amount

.05x + .40 ( 10-x) = .20 (10)

.05x + 4 - .4x = 2

-.35x = -2

x = 5.7 liters of 5 % 10 - 5.7 = 4.3 liters of 40%