11. . Product A is made of two units of B and three unit of C. B is made of one unit of D.  A, B, and D, and have lead times of one week, and C has a lead-time of two weeks. The demand for product A is 550 units in the fourth week and 600 units in the sixth week.

• Draw the product structure tree.'
• Develop the MRP schedule given there are 75 units of B on  hand; for other items, on hand quantities are zero. (Assume safety stock and  scheduled receipt are zero for all items; lot size for each item = 400) 

12.  Use CPM (AON modeling) to determine

(a)        ES, LS, EF and LF for each of the following activities (Draw a network diagram for getting any credit).  Also, determine slack  (sometimes referred to as total slack) and free slack for each activity.

(b)        Determine the critical path (that is, which activities are most critical for the timely completion of the project).

Shortest duration for the project completion.

Activity   Duration    Predecessor

              (weeks)

A            5               -

B            3               -

C            6               A

D            3               A

E            8               C,B

F            3               D,E

G            4              F