Who is asking: Student
You should first decide on a common unit for the measurement of length. I am going to use meters. Thus the pipe has a radius of 0.024 m and the water is flowing at 8 000 m/hr. Hence in one hour you are putting into the tank the amount of water that fills a cylinger of height 8 000 m and radius 0.024 m. The volume of a cylinder is pi x radius2 x height and hence you can find the rate that water in flowing into the tank in m3 per hour.
The volume of the tank is 4 x 3 x 2.8 m3 and thus you can calculate the time needed to fill the tank.Cheers,