Question

Joy is preparing 13 liters of a 20% saline solution. She only has 30% and 10% solution in her lab. How many liters of the 30% and how many liters of the 10% should she mix to make the 20% solution?

Answer 1

The volume of `30%` solution is `=6.5L` and volume of `10%` solution is `=6.5L`

Explanation:

Make a material balance with respect to the saline solution

Let the volume of `30%`solution be `=vL`

Then,

The volume of `10%` solution is `=(13-v)L`

So,

`v*30/100+(13-v)*10/100=13*20/100`

Solving this equation for `v`

`30v+(13-v)*10=13*20`

`30v+130-10v=260`

`20v=130`

`v=130/20=6.5L`

The volume of `30%` solution is `=6.5L` and volume of `10%` solution is `=6.5L`