Solve the problem. Round your answer to the nearest tenth, when appropriate.
-A toy rocket is shot vertically upward from the ground. Its distance in feet from the ground in $t$ seconds is given by $s(t)=-16 t^{2}+177 t$. At what time or times will the ball be $221 \mathrm{ft}$ from the ground?
A) 171.8 and $182.2 \mathrm{sec}$
B) $5.5 \mathrm{sec}$
C) $11.1 \mathrm{sec}$
D) 1.4 and $9.6 \mathrm{sec}$

Question

Quizplus · Accepted Answer

To find when the rocket will be 221 ft from the ground, set $s(t) = 221$ and solve for $t$: $221 = -16t^2 + 177t$. Rearranging gives $16t^2 - 177t + 221 = 0$. Solving this quadratic equation yields $t = 1.4$ and $t = 9.6$ seconds.

Solve the Problem ttt Seconds Is Given By s(t)=−16t2+177ts(t)=-16 t^{2}+177 ts(t)=−16t2+177t at What Time or Times Will the Ball Be

Solve the Problem $t$ Seconds Is Given By $s(t)=-16 t^{2}+177 t$ at What Time or Times Will the Ball Be