Question 913026
Intuitively, if we mix equal amounts of the 3% and 7% solution, we should obtain a 5% solution (e.g. if we have 100 mL of the 3% and 100 mL of the 7%, we will have 200 mL, of which 10 mL is acid, 5%).


Hence we must have 60 mL of 3% solution and 60 mL of 7% solution.