Please help me! Math genuises!?

Question

4)to estimate the height of a building, a stone is dropped from the top of the building into a pool of water at ground level. how high is the building if the splash is seen 6.8 seconds after the sone is dropped? Position function given: -4.9t^2 + vt + s t

Answer 1

Acceleration of the stone 32 Ft./Sec/Sec
32 x 6.8 = 217.6 Ft./Sec
Avg. Velocity (0 -> 217.6) 217.6/2 = 108.8 Ft./Sec.
Dist traveled 108.8 Ft./Sec. x 6.8 Sec. = 739.84 ft.

Answer 2

To find these i think u need to use the formula x=ut+1/2at2
Since dropped from rest u is zero.
X is the displacement
so x=0*6.8+0.5*9.8*(6.8)2
x=226.6m
x=227m(correct to 3 s.f)