Question 59845
Your formula has a slight error, it should be:
{{{s(t) = -16t^2 + 32t}}} The x^2 coefficient should be negative.  This is because the effects of gravity act in a downwards (negative) direction.

The graph looks like:
{{{graph(300,200,-5,5,-5,20,-16x^2+32x)}}}
From the graph, the maximum value of the height (y-value) is 16 feet.