Answer:
That is an indeterminant question, as we do not know the amount of fax time used of each machine and it certainly won't be equal. However, based on whats given you could say
Step-by-step explanation:
5 hrs. use / 0.25 service time = 20 / 3 machines = 6.67. Probability of needing to service 2 machines simultaneously is: 1/6.67 = 15%.