Final answer:
The total volume of the solution after mixing 40.0 mL of 0.24 M KOH with 60.0 mL of 0.15 M Ba(OH)2 is 100.0 mL.
Step-by-step explanation:
When KOH is added to Ba(OH)2, the total volume of the solution is assumed to be the sum of the individual volumes, as no significant volume change occurs when two solutions are mixed.
Thus, the total volume of the solution after mixing 40.0 mL of 0.24 M KOH and 60.0 mL of 0.15 M Ba(OH)2 is simply the sum of the two volumes: 40.0 mL + 60.0 mL = 100.0 mL.