Question

A chemist has 20% and 40% solutions of acid available. How many liters of each solution should be mixed to obtain 180 liters of 22% acid solution?

Answer 1

Explanation:

x = liters of the 20% solution

y = liters of the 40% solution

we know

x + y = 180

and therefore

x = 180 - y

0.2x + 0.4y = 0.22×180

0.2(180 - y) + 0.4y = 39.6

36 - 0.2y + 0.4y = 39.6

0.2y = 3.6

y = 3.6/0.2 = 18 liters

x = 180 - y = 180 - 18 = 162 liters

the chemist needs to mix 162 liters of the 20% solution and 18 liters of the 40% solution to get 180 liters of a 22% solution.