If a Ball Is Thrown into the Air with a Velocity

Multiple Choice

If a ball is thrown into the air with a velocity of $58 \mathrm { ft } / \mathrm { s }$ , its height (in feet) after $t$ seconds is given by
$$H = 58 t - 9 t ^ { 2 } .$$
Find the velocity when $t = 9$ .

A) $- 101 \mathrm { ft } / \mathrm { s }$
B) $- 104 \mathrm { ft } / \mathrm { s }$
C) $- 106 \mathrm { ft } / \mathrm { s }$
D) $- 103 \mathrm { ft } / \mathrm { s }$
E) $- 99 \mathrm { ft } / \mathrm { s }$