A large induction motor is usually started by applying a reduced voltage across the motor; such a voltage may be obtained from an autotransformer. A motor is to be started on 50% of full load torque, and the full-voltage starting current is 5 times the full-load current. The full-load slip is 4%. Determine the percentage reduction in the applied voltage (i.e., the percentage tap on the autotransformer).