=+50. Even under the increased levels of security sought by current airport security practices, airports try to assure rapid processing of individuals through security checkouts. In an experiment designed to find combinations of factors that will minimize travelers’

processing times at security checkpoints, three factors were studied: the number of ticket checkers (2 or 3), the number of X-ray machines (1 or 2), and the number of metal detectors (1 or 2) (“Operation