The product structure tree for end item E follows.

a$)$ The manager wants to know the material requirements for the ordered part R that will be

needed to complete $120$ units of E by the start of week $5.$ Lead times for items are one week

for level $0$ items, one week for level $1$ items, and two weeks for level $2$ items. There is a

scheduled receipt of $60$ units of M at the start of week $2$ and $100$ units of R at the start of

week $1.$ Lot$-$for$-$lot ordering is used. To answer this question, MRP schedules $($tables$)$ for

$$E$,$M$,$ and $$R$$ are needed.

b$)$ How many units of $$N$$ are required to produce $120$ units of E$,$ given that we have $100$ units

of $$I$$ in stock?