[tex]\\$Velocity = $\frac{Displacement}{total time}$;[/tex]
[tex]s(t) = -16t^2+128t\\\\$a) \\$Vel_1 = \frac{s(4) - s(1)}{4 - 1} = \frac{144}{3} = 48\\$b)\\$Vel_2 = \frac{s(3) - s(1)}{3-1} = \frac{128}{2} = 64\\$c)\\$Vel_3 = \frac{s(2) - s(1)}{2-1} = \frac{80}{1} = 80\\$d)\\$Vel_4 = \frac{s(1+h) - s(1)}{1+h-1} = \frac{-4h(h+6)}{h} = -4h - 24[/tex]