Calculation of mutual inductance between the two coils

A long single layer solenoid has an effective diameter of 10 cm and is wound with 2500 AT/meter. There is a small concentrated coil having its plane lying in the centre cross-sectional plane of the solenoid. Calculate the mutual inductance between the two coils in each case if the concentrated coil has 120 turns on an effective diameter of (a) 8 cm and (b) 12 cm.