Hi i am having problem on answering these question may need STAT Graphic Thank you.

11. Mailing Machine Malfunctions. A technician services mailing machines at companies in the Phoenix area. Depending on the type of malfunction, the service call can take 1, 2. 3, or 4 hours. The different types of malfunctions occur at about the same frequency. a. Develop a probability distribution for the duration of a service call. b. Draw a graph of the probability distribution. c. Show that your probability distribution satises the conditions required for a discrete probability function. d. What is the probability a service call will take three hours? e. A service call has just come in. but the type of malfunction is unknown. It is 3:00 RM. and service technicians usually get off at 5:00 RM. What is the probability the service technician will have to work overtime to fix the machine today