5. The historical data of a given transformer shows that in the absence of preventive maintenance actions; the transformer will fail after Z vears. In the end of year 3 ; the transformer enters to the minor deterioration (D2) state and in the end of year 5 enters to the major state (D3). The electric utility intends to run preventive maintenance regime to increase the useful age of the transformer. The regime includes two maintenance actions. The minor maintenance will be done when transformer enters to the minor state (D2) and the maintenance group is obliged to shift the transformer to healthy state (D1) in two months. The major maintenance will be done in the major state (D3) and the state of transformer should be shifted to the healthy state (D1) in one month. Calculate the value of transformer age increment due to this regime. Z : the average value of student number