The solution to the problem is as follows:
'(t) = 0 gives:
-24t + 60 = 0
t = 2.5
For this t, the second derivative s"(t) = -24 is negative.
And so, s(t) is maximum for t = 2.5.
Maximum height is:
S = -12(2.5)^2 + 60(2.5) +8 = 233ft
I hope my answer has come to your help. God bless and have a nice day ahead!
