Question 969451
If we graph f(t)=-16t^2 + 80t  + 384, we'd see a convex upward parabola. The ordinate scale is 75 feet per tick. The vertex has a t value (x-axis) equal to  -b/2a, where b  is the coefficient of the middle term, and a is the coefficient of the leading term. 

Vertex t value is therefore (-80/-32)=+2.5 seconds=t

Height is (-16)(2.5^2) + 80(2.5) + 384


Height=-100 + 200 + 384= 484 feet.

{{{graph(300,200,-0.2,8,0,500,-(16x^2)+80x+384)}}}