Only solve part a$)$ and part b$),$ thank you.

Problem $3.$ A student ties a rubber stopper of mass $0\mathrm{.}100kg$ to a string and whirls the stopper in a perfectly horizontal circle at a rate of $1\mathrm{.}5$ revolutions per second. The radius of the stopper's motion is $0\mathrm{.}50$ meters.

$($a$)$ Calculate the average speed of the rubber stopper.

$($b$)$ Calculate the average kinetic energy of the rubber stopper.

$($c$)$ Based on your answer to part $($b$),$ calculate the rotational inertia I of the rubber stopper. $($Recall that the kinetic energy of a rotating point mass is given by $KE=\frac{1}{2}|{}^2|,$ where $$ is the angular speed in radians per second.$)$