Answer:
about 71.6 mH
Step-by-step explanation:
The impedance of the inductor is the ratio of voltage to current:
Z = (36 V)/(0.2 A) = 180 Ω
This is the product of the inductance and the radian frequency of the voltage source:
Z = ωL = 2πfL
L = Z/(2πf) = 180/(2π·400) ≈ 0.0716 . . . . Henries
The inductance is about 71.6 mH.