A clinic has four different physicians. A, B, C, and D, one of whom is selected by each new patient. If the new patients are equally likely to choose each of the four physicians independently of each other, estimate the probability that physician A will get at least 25 out of the next 80 new patients. If physician D leaves the clinic and the new patients are equally likely to select each of the remaining three physicians, what then is the probability that physician A will get at least 25 out of the next 80 new patients?