This work applied the principle of input probability to model and simulate a queuing or waiting system. The queuing or waiting system is an automobile maintenance and repair workshop. Different types of Scheduling methods were discussed while effort is focused on priority dispatching scheduling. This work will assist Maintenance Engineers and Managers in determining the optimal number of technicians or artisans needed to be employed in a maintenance workshop. This work if followed religiously by Maintenance Engineers and Managers will enhance decision making.