A centrifuge is a common laboratory instrument that separates components of differing densities in solution. This is accomplished by spinning a sample around in a circle with a large angular speed. Suppose that after a centrifuge in a medical laboratory is turned off it continues to rotate with a constant angular deceleration for 10.9 s before coming to rest. If its initial angular speed was 3691 rpm, what is the magnitude of its angular deceleration? How many revolutions did the centrifuge complete after being turned off?