Finding Avogadro's Number?

A student adds 25 drops of cetyl alcohol in hexane, (solution concentration 1.08 x 10^-4 g/mL) to form a monolayer of the alcohol on the surface of water in a petri dish with an area of 241 cm^2. The cetyl alcohol molecules are cylindrical with the diameter of the cylinder equal to one fifth of the length.... show more A student adds 25 drops of cetyl alcohol in hexane, (solution concentration 1.08 x 10^-4 g/mL) to form a monolayer of the alcohol on the surface of water in a petri dish with an area of 241 cm^2.

The cetyl alcohol molecules are cylindrical with the diameter of the cylinder equal to one fifth of the length. Assume the long axis of the cylinder is perpendicular to the water surface. The Medicin dropper used in this experiment was calibrated at 81 drops per milliliter. Using the above data and model, calculate Avogadro's number. (Hint: the volume of a cylinder is v=(Pi)(r^2)(h), r = radius, h = height, and r = (t/10).)

Sorry to ask this, but i've been working on this one problem since Thursday of last week and try as I might, I cannot figure it out. Please help me!
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