An oil engine works on the Dual cycle, the heat liberated at consent pressure being twice that liberated at consent volume. The compression ratio of the engine is 8 and the expansion ratio is 5.3. But the compression and expansion process follows the law PV1.3 = C. The pressure and temp. at beginning of compression are 1 Bar and 27oC respectively. considering Cp =1.004 KJ/Kg oK and Cv =0.717 KJ/Kg oK for air, determine air standard efficiency and mean effective pressure.