How much water is added to 5.28 grams of ethanol to get a concentration of 1.67M?
This question can't be answered without knowing the density of the solution. However, we CAN calculate what volume we need.
5.28 g ethanol = how many moles. moles = grams/molar mass = 5.28/46 = 0.11 moles (I have rounded here and there so you need to do it more carefully.)
M = moles/L; therefore, for 1.67 M and 0.11 moles, we need L = 0.11 moles/1.67 M = about 0.070 L or about 70 mL of SOLUTION. That means the total volume of ethanol + water = that volume and NOT 70 mL water added.