Monkey poop

[Dillinger4]

A monkey escapes from his cage at the zoo and climbs to the top of a building. He poo's in his hand and throws it off the side. It takes the poo 4 seconds to hit the street below. How far did the poo fall?

[Dillinger4]

I come up with the following.

The poo should fall at a rate of g which is equivalent to 9.8m/s so the poo should hit the ground at a final velocity of 32.2m/s. The average should be i_v + f_v / 2 = a_v which comes out to 19.6m/s. So then the distance should end up being 78.4m using d = a_vt.

f_v = 39.2m/s
a_v = 19.6m/s
d = 78.4m