An airline predicts the following pilot requirements for the next 5 quarters: 80, 90, 110, 120, 110. Current staff consists of 90 pilots. The question of major concern is the number of pilots to hire in each of the next 5 quarters. A pilot must spend the quarter in which she/he is hired in training. The airline's training facilities limit the number of pilots in training to at most 15. Further, the training of pilots requires the service of experienced pilots at the ratio of 5 to 1, i.e. 5 pilots in training require 1 experienced pilot. An experienced pilot so assigned cannot be used to satisfy regular requirements. The cost of hiring and training a pilot is estimated at $20,000 exclusive of the experienced pilot time required. Experienced pilots cost $25,000 per quarter. Company policy does not include firing pilots