A software company has found that on Mondays, the polynomial function C(t) = −0.0625t4 + t3 − 6t2 + 16t approximates the number of callers to its hotline at any one time. Here, t represents the time, in hours, since the hotline opened at 8:00 A. M. How many service technicians should be on duty on Mondays at noon if the company doesn't want any callers to the hotline waiting to be helped by a technician?