The h in the question would be 100ft which was the wall height. The v should be 100ft/sec. The ball is launched from the base so the hi would be 0.
The calculation would look like this:
h= -16t^2 + v*t + h
100= -16t^2 + 100*t + 0
-16t^2 + 100t - 100=0 -----> divide by -4
4t^2 -25t + 25 =0 -----> split -25t into -20t and -5t
(4t^2 -20t) (-5t + 25) =0 -----> simplfy
4t (t -5) -5 (t -5) =0
(4t-5) (t-5)
t= 5/4=1.25 ; t= 5
The ball will be higher than the wall at 1.25< t <5
