Answer
1,2
Work Step by Step
We are given the following equation:
$$ h=48t-16t^2$$
Thus, plugging in $32$ for $h$, we find:
$$32=48t-16t^2 \\ -16t^2+48t-32=0 \\ t_{1,\:2}=\frac{-48\pm \sqrt{48^2-4\left(-16\right)\left(-32\right)}}{2\left(-16\right)} \\ t=1,2$$