Please help with the following Physics question on Magnetism and Electricity

(c) An apprentice sets up the circuit shown in Figure 3.1 to study the magnetic flux density B inside a solenoid. The magnetic probe was placed inside the solenoid to take direct reading of the flux density for various currents /. A set of results are given in the table below. Solenoid Magnetic Probe Figure 3.1 B 120 240 360 480 600 720 (mT 840 960 1080 I (A) 0 50 100 150 200 250 300 350 400 450 i) Plot a graph of B vs / on the graph paper in the back of your answer booklet. ii) What is the relationship between B and I from the plotted graph? iii) Find the gradient of your graph. iv) Using B = Henl for the magnetic flux density inside the solenoid, where n is the number of turns per unit length. Find the constant go if n = 1100 turns per meter. [15]