A. We're told the fan completes 45 full revolutions every minute. One full revolution is
, so the fan has an angular speed of

B. Throughout one full revolution of the fan, a point at the tip of one of the fan's blades travels the circumference of a circle with radius 16 in. The circumference is then
. This means the linear speed is

You divide 690 by 100 which is 6.9
Therefore, one 50cent coin is 6.9g