A two-winding single-phase transformer rated 65 kVA, 480/1920 V, 60 Hz, has an efficiency of 0.96 when operated at rated load, 0.8 power factor lagging. This transformer is to be utilized as a 2400/1920-V step-down autotransformer in a power distribution system. (a) Find the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the ratings as a two-winding transformer. Assume an ideal transformer. (Round your answer to at least one decimal place.) kVA (b) Determine the efficiency of the autotransformer with the kVA loading of part (a) and 0.8 power factor leading. (Enter your answer as a decimal or fraction. Round your answer to at least three decimal places.) ????auto =