A man stands on a platform that is rotating $($without friction$)$ with an angular speed of $2\mathrm{.}11$ rev$/$s; his arms are outstretched and he holds a brick in each hand. The rotational inertia of the system consisting of the man, bricks, and platform about the central axis is $5\mathrm{.}38$ kg$$m$^2.$ If by moving the bricks the man decreases the rotational inertia of the system to $2\mathrm{.}69$ kg$-$m$^2,($a$)$ what is the resulting angular speed of the platform and $($b$)$ what is the ratio of the new kinetic energy of the system to the original kinetic energy?