A bolt is dropped from a bridge under construction, falling $90$ m to the valley below the bridge. $($a$)$ How much time does it take to pass through the last $11\%$ of its fall? What is its speed $($b$)$ when it begins that last $11\%$ of its fall and $($c$)$ just before it reaches the ground?

$($a$)$ Number $$ Unit

$($b$)$ Number $$ Unit

$($c$)$ Number $$ Unit