An operator introduces a step change in the flow rate q_i to a particular process at 3:05 A.M., changing the flow from 500 to 520 gal/min. The first change in the process temperature T (initially at 120^∘F) occurs at 3:08 A.M. After that, the response in T is quite rapid, slowing down gradually until it appears to reach a steady-state value of 124.7^∘F. The operator notes in the logbook that there is no change after 3:34 A.M. What approximate transfer function might be used to relate temperature to flow rate for this process in the absence of more accurate information? What should the operator do next time to obtain a better estimate?