456.5 ml When we dilute the solution, the total number of moles of NaOH won't change. And since the number of moles is volume multiplied by molarity, we can create the following equality. 80.00 * 9.13x10^-2 = V * 1.60x10^-2 Now solve for V 80.00 * 9.13x10^-2 = V * 1.60x10^-2 7.304 = V * 1.60x10^-2 456.5 = V So you need to dilute the 80.00 ml of solution to 456.5 ml in order to reach the desired molarity.