A steam engine functions by converting liquid water to steam, which is then used to drive a rotating shaft. This engine contains 2 engineering devices: the boiler where the liquid water is converted to steam and the turbine where the steam is used to drive the shaft. Let the fuel used in the boiler be wood with a heating value of 15 MJ/kg (i.e. when 1 kg of wood is burned 15MJ of energy is released). When .1 kg of fuel was burned the shaft output was measured to be 567 kJ. Assuming the turbine is 90% efficient, what is the efficiency of the boiler?