Respuesta :

(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