1. The problem statement, all variables and given/known data Pressure in vacuum is 10^-3 Torr. External Pressure is 1atm and 300K. Pinhole of 10^-10cm^2 made in vacuum. Assuming all molecules striking hole pass through, how many molecules leak into vacuum in 1hour? Answer: 10^17 molecules 2. Relevant equations Flux = <v>*N/4V Rate = Flux times A 3. The attempt at a solution I can make an DE: dN/dt = <v>N/4V*A and solve this but I have no info on N0, initial molecules. I also don't have volume. So I don't see how to obtain a numerical result.