Answer:
Maximum height reached = 159.25 feet
Explanation:
We have the equation h(t)=-16t²+100t+3
At maximum height derivative is zero.
That is

Substituting t = 3.125 s in h(t)=-16t²+100t+3
Maximum height
h(3.125) = -16 x 3.125²+100 x 3.125 + 3 = 159.25 feet
Maximum height reached = 159.25 feet