In a manufacturing company at present, the pattern shop and the maintenance department are located in the same room. One large counter is used by both maintenance personnel to get tools and parts and by sand molders that need various patterns for the molding operation. Peter and Bob, who work behind the counter, are able to service a total of 10 people per hour (or about 5 per hour each). On the average, 4 people from casting/maintenance and 3 people from the molding/pattern department arrive at the counter per hour. People from the molding department and from casting dept arrive randomly, and to be served they form a single line. Pete and Bob have always had a policy of first come, first served. This is a poisson arrival pattern exponential service time model. Because of the location of the pattern shop and casting department, it takes about 6 minutes for a person from the casting/maintenance department to walk to the counter, and it takes about 2 minute for a person to walk from the molding. Separating the maintenance shop from the pattern shop had a number of advantages. It would take people from their department only 2 minutes now to get to the department counter. Using time and motion studies, George was also able to determine that improving the layout of the maintenance department would allow Bob to serve 6 people from the maintenance department per hour, and improving the layout of the pattern department would allow Pete to serve 7 people from the molding shop per hour. This would act as a single server system for both the departments separately. In the present system how much minutes are spent in casting ? Give only numeric answer