An object falling in a vertical line passes a window 3 m high in 1/6 seconds. Find the distance above the top of the window from which the object let fall.

No idea about this question at all.

I did

a=9.8

thus v^2 = 19.8x

at v=18 (at end of window)

x=16.5

thus origin above window = 13.5

However answer is 15.06