The ‘mission time’ that guides the design of a manufactured item as also its ‘design life’ which incorporates ‘safety factors’ to ensure that the item does not fail before the mission time, are always finite. In stress-strength analysis, both stress encountered by the product during use or deployment and strength built into the product through its design and conformance of manufacture to design do vary over finite ranges. Time to repair of a failed product or time between two consecutive repairs is also finite. Besides these continuous variables, number of successful operation cycles before failure or number of repairs before eventual disposal of a product and similar other discrete variables have finite ranges of variation.