Manipal Entrance Test 2014 Physics Paper

Two litre of water at initial temperature of 27°C is heated by a heater of power 1 kW. if the lid of kettle is opened, then heat is lost at the constant rate of 160 J/s. Find, the time required to raise the temperature of water to 77°C with the lid open (specific heat of water 4.2 kJ/kg)