### Molecules in vacuum

In an ultra-high vacuum system, the pressure is measured to be 1.00 * 10^-10 torr, the average molecular diameter is 1.00 * 10^-10 m, the average molecular speed is 500 m/s and the temperature is 300 K. Find the number of molecules in a volume of 1.00 m^3 and the mean free path of the molecules.