A 4-pole, 50 Hz, slip ring induction motor has rotor resistance and standstill reactance referred to stator of 0.2 ohm and 1 ohm per phase respectively. At full load it runs at 1440 rpm. Determine the value of resistance to be inserted in rotor in ohms per phase to operate at a speed of 1200 rpm, if (a) the load torque remains constant, (b) the load torque varies as the square of the speed. Neglect stator resistance and leakage reactance. Assume a ratio of stator to rotor turns of 1.1.