The Ace Machine Company is considering using a priority scheduling rule in its fabrication shop and must decide whether to use: the critical rule, the order slack rule, the shortest operation next rule or the slack per operation rule. The table below shows the company's current inventory and shop status. Exhibit 1 Note: Time is measured in days. Manutacturing lead time remaining includes both the machine processing time and the length of time orders spend moving and waiting to be processed in a machine queve. Current operating processing time (as well as total processing time remaining) includes no mave or queue times. a) State the formula for calculating the priority index for each of sequencing rules given above. b) Compute the scheduling priority index for each order in Exhibit 1 for the four sequencing rules