Te earths magnetic field with a magnetic dipole moment of

Question

Question: The earth's magnetic field, with a magnetic dipole moment of 8.5×10²²A•m², is generated by currents within the molten iron of the earth's outer core. (The inner core is solid iron.) As a simple model, consider the outer core to be a current loop made of a 1200-km-diameter "wire" of molten iron. The loop diameter, measured between the centers of the "wires", is 3080 km.

Part A- What is the current in the current loop?

Answer in A

If possible just a brief explanation how you got the answer? Thanks.