Finding the radius of a cylinder

Hello,

I am a very new member that had not made a new account because I was banned or anything ;-)

Can anyone please show me how to answer the following question: (my exam is tomorrow so please the sooner the better)

Water comes from a cylindrical tank.

When 2 cubic metres of water leave the tank, the level of water in the tank goes down by 1.3 **millimeters**. Calculate the radius of the tank, in **metres**, correct to one decimal place.

the answer is r= sqrt(2/pie*0.0013) = 22.1

Thanks

IBstudent, ow sorry I mean IGCSEstudent :)