idk how to do this

Question

Leon begins with 72 milliliters of an 8% saline solution. He adds x milliliters of distilled water to the saline solution. a. What function represents salt concentration, C, of the new solution? b. What is the approximate concentration if 720 milliliters of distilled water is added?

Answer 1

Since the solution is made with pure (100%) water, the other solutions must be in terms of water.

Therefore the 8% saline becomes 92% water.

 

.92(72) + 1x = C(72 + x)

 

For 720 milliliters

 

.92(72) + 720 = C(792)

66.24 + 720 = 792C

786.24 = 792C

0.9927 = C

 

The concentration of the water is 99.27, so the concentration of the saline is 0.0073 or 0.73%.