Question

A hospital needs 80 liters of a 12% solution of disinfectant. This solution is to be prepared from a 33% solution and a 5% solution. How many liters of each should be mixed to obtain this 12% solution? There are different ways to solve this problem, but using a system of equations is the simplest way

Answer 1

Answer: 20 L of 33% solution and 60 L of 5% solution should be mixed

Explanation:

0.33x + 0.05(80-x) = 0.12*80

0.33x + 4-0.05x = 9.6

0.33x - 0.05x = 9.6-4

0.28x = 5.6

x = 5.6/0.28

x = 20 L of 33% solution should be used

80-20 = 60 L of 5% solution should be used

Proof:

0.33*20 + 0.05*60 = 0.12*80

6.6 + 3 = 9.6

9.6 = 9.6