Hi i have been trying to do this question and have got till part two but am unable to do part 3.

A cubical tank of side 2m is filled with water to a height of h (m). The water is drained through a circular hole of diamter 0.2m.

i)Obtain a differential equation giving the height h at any time t.

ii) Given that when t=0, h=1.3 solve this differential equation to give an expression for h in terms of t.

iii) How long ( in minutes and seconds) does it take to empty the tank if it is 1.3m full.