1. The problem statement, all variables and given/known data Gas escapes from a leaky cylinder so that the rate of decrease of pressure in the cylinder is proportional to P - Patm where P is the pressure in the cylinder and Patm is atmospheric pressure (1.0 atm). The initial pressure in the cylinder is 1.1 x 103 atm. If the rate of pressure decrease is 0.28 atm/min when the pressure in the cylinder is 8.5 x 102 atm, how many days will it take the pressure in the cylinder to drop to 1% of its initial value? 2. Relevant equations dp/dt is proportional to P - Patm 3. The attempt at a solution This appears to be a simple problem where my challenge is simply to set up the calculus problem to solve, however, I am having trouble with this. The rate of the effusion of the gas from the leak is connected to the amount of the gas still in the cylinder less 1 atm. The one data point given in the problem should allow me to determine some sort of constant of proportionality.