Solve the Problem $\mathrm{h}=480-16 \mathrm{t}^{2}$ How Many Seconds Will It Take for the Rock

Multiple Choice

Solve the problem. Round your answer to the nearest tenth, when appropriate.
-A rock falls from a tower that is 480 feet high. As it is falling, its height is given by the formula $\mathrm{h}=480-16 \mathrm{t}^{2}$ . How many seconds will it take for the rock to hit the ground $(\mathrm{h}=0)$ ?

A) $5.5 \mathrm{sec}$
B) $21.5 \mathrm{sec}$
C) $21.9 \mathrm{sec}$
D) $14,400 \mathrm{sec}$