Answer
$68$ ft
Work Step by Step
Let's compare $f(x)=-16x^2 + 48x + 32$ to $f(x)=ax^2+bx+c$. We can see that $a=-16, b=48, c=32$. $a\lt0$, hence the graph opens down, and so its vertex is a maximum. The maximum value is at $x=-\frac{b}{2a}=-\frac{48}{2\cdot(-16)}=1.5.$ Hence, the maximum value is $f(1.5)=-16(1.5)^2+48(1.5)+32=68.$
