A turbojet engine is tested in the laboratory under conditions simulating an altitude where atmospheric pressure p = 785.3 psfa, temperature T = 429.5°R, and specific weight γ = 0.0343 lb/ft³. If the exit area of the engine is 1.50 ft² and the exit pressure is atmospheric, what is the Mach number Ma if the gross thrust is 1470 Ib? (Use k = 1.33.)