Q:  What is the value of the pressure derivative in this shell?

    
        dP/dr  =  - 1.21 x 10^(-2)    dyne/cm^2/cm



  Q:  What is the pressure of the next-inner shell?


        P_new  =  P_old                   +  (dP/dr) * dr

               =  2.93 x 10^6 dyne/cm^2   +  (-1.21 x 10^(-2) dyne/cm^2/cm) * (-7.1 x 10^7 cm)


               =  2.93 x 10^6 dyne/cm^2   +  8.61 x 10^5 dyne/cm^2


               =  3.79 x 10^6 dyne/cm^2