A toy rocket is shot vertically upward from the ground. Its distance in feet from the ground in $t$ seconds is given by $s ( t ) = - 16 \left( t ^ { 2 } \right) + 175 t$. At what time(s) will the ball be $162 \mathrm { ft }$ from the ground? Round your answer to the nearest tenth of a second.
A) 169.8 sec and 180.2 sec
B) 5.5 sec
C) 10.9 sec
D) 1.0 sec and 9.9 sec

Question

Quizplus · Accepted Answer

To find when the ball will be 162 ft from the ground, set $s(t) = 162$ and solve for $t$. This gives the equation $-16t^2 + 175t = 162$. Rearranging, we get $-16t^2 + 175t - 162 = 0$. Solving this quadratic equation for $t$ yields the times when the ball is at 162 ft. The correct solutions are approximately 1.0 sec and 9.9 sec.

A Toy Rocket Is Shot Vertically Upward from the Ground ttt

A Toy Rocket Is Shot Vertically Upward from the Ground $t$