1. The problem statement, all variables and given/known data Treat the atmosphere as an ideal gas with a uniform temperature of 200 K. Find the density at 20 km. R= 260 N*m/(kg*k) g= 3.92 m/s^2 rho(0)= 0.015 kg/m^3 2. Relevant equations P=rho*R*T dp/dz= -rho*g 3. The attempt at a solution I found the pressure at ground level using P=rho*R*T P=(0.015 kg/m^3) (260 N*m/(Kg K)) (200 K) = 780 N/m^2 I'm not sure how to proceed from here.