$1.$ Group assignment question, waiting line model

During the campus Spring Fling, the bumper car amusement attraction has a problem with cars

becoming disabled and in need of repair. One repairer can fix cars in an average time of $25$

minutes. Cars tend to break down at the rate of two per hour. Assuming that there is only one

repair person, the arrival rate follows a Poisson distribution, and the service time follows an

exponential distribution.

a$)$ On average, how long is a disabled bumper car out of service waiting to be repaired?

b$)$ On average, how many disabled bumper cars are out of service and not able to take riders on

the bumper car attraction?

c$)$ When a bumper car becomes disabled, what is the probability that it will find that there is at

least one other bumper car already waiting to be repaired?