60.00 mL of 0.817-M HNO_{3} solution and 65.00 mL of 0.174-M HNO_{3} solution are combined and then diluted with water until the total volume is 250.00 mL.

1. Find the amount of liters of each solution, because molarity is in liters. (0.06000 L 0.817-M solution and 0.6500 L 0.174-M solution)

2. Use the molarities to figure out how many moles of HNO3 you have. [ a) .06 L * 0.817 mol HNO3/1 L solution = 0.04902 mol HNO3 b) .065 L * 0.174 mol HNO3/1 L solution = 0.1131 mol HNO3 ]

3. Add the number of moles from both solutions together. (0.04902 mol HNO3 + 0.1131 mol HNO3 = 0.06033 mol HNO3 total

4. Divide by new, diluted volume (in liters). 0.06033 mol HNO3/0.25000 L solution = 0.24132-M solution.

5. Significant figures: Go back to the problem and see which one has the least amount of significant figures. you use 3 significant figures, giving an answer of 0.241-M solution.