A South American country has 17 planes in its air

A South American country has 17 planes in its air force. They are short on money and do not want to spend any more than necessary to keep the planes in running condition. The cost to perform preventive maintenance on all 17 planes is $16,000 in local dollars. If a plane has a malfunction between preventive maintenance, it costs $5,000 (local dollars) to while the plane is out of service for repairs and other related costs (referred to as the breakdown cost). The malfunction history on the planes is as follows.

a) How often should preventive maintenance be performed based on a cost analysis?

b) What is the breakdown cost that would equate the monthly total maintenance strategy for a two-month PM cycle with a three-month PM cycle? For this analysis, assume that except for the cost of a breakdown all other data (facts and figures) are the same as given in the original problem statement.