A professor stevens wants to mix a solution (a mixture of substance and water) containing 13% acid with one containing 18% acid to obtain a 50 millimeter solution containing 16% acid. How many milliliters of the 13% solution should the professor use?

20 ml 13% solution should the professor use

Explanation:

Let

             the volume of the 13% solution should the professor use = a

So, according to question

                        13% x a + 18% x (50-a) = 50 x 16%

                 ⇒      0.13 a   + 0.18 x 50 - 0.18 a = 50 x 0.16

                 ⇒     - 0.05 a = 8 - 9

                 ⇒        

So, 20 milliliters of the 13% solution should be the professor used.

        & (50 - 20) = 30 ml of the 18 % solution would be use.