Wrong answer! In a twin with propellers mounted on the wings. 1/2 ball towards the good engine is closer to zero side slip, with the failed engine fully feather. It is closer to full ball if windmilling. I make a point of demonstrating this to my ME students on the second flight by attaching a piece of yarn to the center of the windshield and setting one engine to zero thrust, then windmilling the engine. each time fiddling with the pedal to get the yarn aligned with the center post, then look at the ball.