Carousel conveyors are used for storage and order picking for small parts. The conveyors rotate clockwise or counterclockwise, as necessary, to position storage bins at the storage and retrieval point. The conveyors are closely spaced, such that the operator’s travel time between conveyors is negligible. The conveyor rotation time for each item equals 1 minute; the time required for the operator to retrieve an item after the conveyor stops rotating equals 0.25 minute. How many carousel conveyors can one operator tend without creating idle time on the part of the conveyors?