Question

Mastering3.3.23Pure acid is to be added to a 10% acid solution to obtain 90L of 40% solution. What amounts of each should be used?How many liters of 100% pure acid should be used to make the solution?

Answer 1

If we add x liters of the pure acid, we must have 90-x liters of 10% acid solution.

The equation that represents the situation:

`\begin{gathered} x+0.1(90-x)=.40(90) \\ x+9-0.1x=36 \end{gathered}`

Solve for x to determine the liters of pure acid:

`\begin{gathered} 0.9x=36-9 \\ 0.9x=27 \\ x=(27)/(0.9) \\ x=30 \end{gathered}`

30 liters of pure acid need to be used to make the solution.

Then, 90-x would be the amount of the 10% acid solution:

`90-30=60`

60 Liters of 10% acid solution is needed to make the solution.