Based on the technical specifications of the Buck $($Step$-$down$)$ power converter circuit provided below, determine the following:

a$)$ Calculate the duty cycle.

b$)$ Calculate the inductor ripple $($fluctuation$)$ current.

c$)$ Calculate the output voltage ripple $($fluctuation$)$ value.

d$)$ Calculate the critical inductance value for inductor selection.

e$)$ Calculate the critical capacitance value for capacitor selection.