Question

Suppose a chemist combines a 25% acid solution and a 50% acid solution to make 40 L of 45% acid solution. How many liters of each solution did she use? Use the blanks below to fill in your numerical answers.

Answer 1

The number of liters for :

Acid solution a = x = 8 liters

Acid solution b = y = 32 liters

Explanation:

Let us represent:

The number of liters for :

Acid solution a = x

Acid solution b = y

Suppose a chemist combines a 25% acid solution and a 50% acid solution to make 40 L of 45% acid solution.

x + y = 40 ...... Equation 1

x = 40 - y

25% × x + 50% × y = 45% × 40

0.25x + 0.5y = 18...... Equation 2

We substitute, 40 - y for x in Equation 2

0.25(40 - y)+ 0.5y = 18

10 - 0.25y + 0.5y = 18

- 0.25y + 0.5y = 18 - 10

0.25y = 8

y = 8/0.25

y = 32 Liters

Solving for x

x = 40 - y

x = 40 - 32

x = 8 Liters.

Hence:

The number of liters for :

Acid solution a = x = 8 liters

Acid solution b = y = 32 liters