A constant-area duct is fed by a converging-only nozzle. The nozzle receives air from a large chamber at p1=600 KPa and T1=550 K. The duct has a friction length of 5.3, and it is choked at the exit. What is the pressure at the end of the duct? If 80 percent of the duct is removed, and the conditions at station 1 and the friction factor remain constant, what is the new exit pressure and Mach number?