Answer
$40$ ft
Work Step by Step
$h=-16t^2+48t+4=-16(t^2-3t)+4=-16((t-1.5)^2-2.25)+4=-16(t-1.5)^2+36+4=-16(t-1.5)^2+40$
Thus the vertex of the graph is at $(1.5,40)$, and the maximum height is $40$ ft.
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