An operation is used to machine 10 kinds of parts. The total weekly requirement for all 10 parts is 900. Each part needs 20 secs machining time . Assume that the machine is to be scheduled no more than 90% of its total available time. A normal workweek is 40 Hrs/week, but 4 hours a week is reserved for normal machine preventive and repair maintenance. If the set up for each kind of part is 1 hour : a) what is the maximum number of set ups per week? b) what is the smallest allowable lot size , assuming all batches are the same size, c) To reduce the lot size in b) by 50% , what must the set time be reduced to?