7. (10pts) Use Johnson's Rule to determine the optimum processing sequence for the jobs listed below. Processing Time (minutes) Center 1 20 B 8 42 IT X 2 D 14 E Zb 18 A F Center 2 12 32 8 7-3 Y 7 6 a) Determine the values of X, Y and Z as positive integers between 5 and 35 in the following table. 68.6 X Y 7 14 b) Based on the values of X, Y and Z in part a). what is the optimum processing sequence? Construct a time-phased chart. What is the throughput time of the system? What are the idle times for the two centers? 2% X 8 88 16 20 36 14 36 18 Z 7 21 6 BE