Question: A design engineer is considering the number of levels of redundancy to build into a particular circuit. The circuit will be part of a sensitive piece of equipment with cost estimated at $500 per failure. Each additional level of redundancy costs $100. If each component fails at random at a rate of one failure every five years, what level of redundancy most closely equates the cost of the design with the expected failure cost of the equipment over its 10-year life cycle?