A firecracker shoots up from a hill 150 feet high with an initial speed of 110 feet per second. Using the formula H(t) = −16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

8 seconds

9 seconds

10 seconds

11 seconds

Question

A firecracker shoots up from a hill 150 feet high with an initial speed of 110 feet per second. Using the formula H(t) = −16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

 8 seconds

 9 seconds

 10 seconds

 11 seconds

anonymous · Answer

since s=150, and v=110, you'll need to solve this quadratic for t:  $\large 0=-162t^2+110t+150 $