In a vapour compression refrigeration cycle, the refrigerant enters the compressor in saturated vapour state at evaporator pressure with enthalpy 250 kJ/kg. The exit of the compressor is at 300 kJ/kg. COP of the cycle is 3. The refrigerant after condensation is throttled to evaporator pressure. If the enthalpy of saturated liquid at evaporator pressure is 50 kJ/kg, the dryness fraction at entry to evaporator is ________________.