A cannon ball is launched into the air with an upward velocity of 172 feet per second, from a 4-foot tall cannon. The height $\displaystyle {h}$ of the cannon ball after $\displaystyle {t}$ seconds can be found using the equation $\displaystyle {h}=-{16}{t}^{{2}}+{172}{t}+{4}$.

Approximately how long will it take for the cannon ball to be 290 feet high? Round answers to the nearest tenth if necessary.
units:



How long long will it take to hit the ground?
units: