Employees at the large computer company earn sick leave in one-minute increments depending upon how many hours per month they work. They can then employ the sick leave time any time during the year. Any unused time goes in a sick bank account that they or other employees can employ in the case of emergencies. The human resources department has estimated that the amount of unused sick time for individual employees is uniformly distributed between 0 and 480 minutes. Based on this information, what is the probability that an employee will have less than 20 minutes of unused sick time?