A playground merry$-$go$-$round has a radius of $4\mathrm{.}0$ m and a rotational inertia of $500\mathrm{.}0$ kg$$m$2.$ It is initially spinning at $0\mathrm{.}90$ rad$/$s when a $20-$kg child crawls from the center to the rim. When the child reaches the rim, the angular velocity of the merry$-$go$-$round is

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$0\mathrm{.}73$ rad$/$s $$

$0\mathrm{.}91$ rad$/$s $$

$0\mathrm{.}62$ rad$/$s $$

$1\mathrm{.}1$ rad$/$s $$

$0\mathrm{.}55$ rad$/$s $$