Either one of two cables can fully feed an important node in a power distribution network. Assume that the failure times of the cables are exponential random variables with hazard rates of 0.1year-1 and 0.2year-, respectively. (1) What are the MTTFs of the cables? (6 pts) (2) Consider two maintenance strategies: . Once a cable fails, a maintenance intervention (repair) is immediately performed, and during the maintenance the power distribution is interrupted. . Consider a potential risk that the unbroken cable can fail during the repair of the failed one, repair action is immediately taken when both cables are broken. Consider a cost of 10000 $ for the repair of one cable, and the economic loss of 30000 $ due to power interruption, please estimate the costs on average per year for the two maintenance strategies, respectively. (7 pts*2) Either one of two cables can fully feed an important node in a power distribution network. Assume that the failure times of the cables are exponential random variables with hazard rates of 0.1year-1 and 0.2year-, respectively. (1) What are the MTTFs of the cables? (6 pts) (2) Consider two maintenance strategies: . Once a cable fails, a maintenance intervention (repair) is immediately performed, and during the maintenance the power distribution is interrupted. . Consider a potential risk that the unbroken cable can fail during the repair of the failed one, repair action is immediately taken when both cables are broken. Consider a cost of 10000 $ for the repair of one cable, and the economic loss of 30000 $ due to power interruption, please estimate the costs on average per year for the two maintenance strategies, respectively. (7 pts*2)