6-61 The demand for product S is 100 units. Each unit of S requires 1 unit of T and 0.5 ounce of U. Each unit of T requires 1 unit of V, 2 units of W, and 1 unit of X. Finally, each unit of U requires 0.5 ounce of Y and 3 units of Z. All items are manufactured by the same firm. It takes two weeks to make S, one week to make T, two weeks to make U, two weeks to make V, three weeks to make W, one week to make X, two weeks to make Y, and one week to make Z.

(a) Construct a material structure tree and a gross material requirements plan for the dependent inventory items.

(b) Identify all levels, parents, and components.

(c) Construct a net material requirements plan using the following on-hand inventory data:
Item S T U V W X Y Z On-Hand Inventory 20 20 10 30 30 25 15 10