The dynamic method is used to measure k, a in a fermenter operated at 30C. Data for dissolved-oxygen concentration as a function of time during the re-oxygenation step is as follows: Time (s) CAL (% air saturation) 43.5 53.5 60.0 10 15 20 67.5 70.5 72.0 30 40 50 73.0 73.5 73.5 70 100 130 The equilibrium concentration of oxygen in the broth is 7.9x 10- kg m-3. Determine k a.