A pizza box manufacturer uses a kanban system to control the flow of materials. The boxes are stamped (cut to size) and inked at a rate of 1,500 pizza boxes an hour. The next machine on the assembly line then receives the partially completed boxes every 15 minutes and automatically folds them into boxes. Containers hold 250 flat, inked pizza boxes each.

a. How many kanbans are needed for the folding machine?

b. If management decides to keep 500 partially completed pizza boxes as safety stock, how many kanbans will be needed?