Solenoids-need some guidance!

Question

things are getting tricky for me, can anyone help!?!

Two very long solenoids have the same length, but solenoid A has 19 times the number of turns, 1/5 the radius, and 6 times the current of solenoid B. Calculate the ratio of the magnetic field inside of A to that inside B.

Answer 1

B = μNI/L. Area or radius doesn't affect B. See the ref.

For sol. A, B = 19*6/1 = 114 * value for sol. B.