Solve all parts of the problem, thank you.

Problem $2.$ A merry$-$go$-$round of mass $250kg$ and diameter $6\mathrm{.}0$ meters rotates at a rate of $12rpm.$ A person of mass $80kg$ jumps on the edge of the merry$-$go$-$round.

$($a$)$ What is the initial moment of inertia of the merry$-$go$-$round $($without the person on it$)?$

$($b$)$ What is the final moment of inertia of the merry$-$go$-$round $($with the person on it$)?$

$($c$)$ What is the rate of rotation $($in rpm$)$ of the merry$-$go$-$round with the person on it$?$

$($d$)$ What is the tangential speed of the person as he moves with the merry$-$go$-$round?