In the figure shown, the maximum and minimum currents through Zener diode are

$\text{ When }{V}_i=130v;V_L=V_Z=50v$

$I=\frac{V_i-V_z}{R_s};I=\frac{130-50}{5\times 1000}=\frac{80}{5\times {10}^3}=16\mathrm{mA}$

$I_L=\frac{V_L}{R_L}=\frac{50}{10\times {10}^3}=5\mathrm{mA}$

$I_Z=I-I_L=16-5;I_z=11\mathrm{mA}$

$\text{ When }{V}_i=90\mathrm{V}$

$I=\frac{V_i-V_z}{R_s}=\frac{40}{5\times {10}^3}=8\mathrm{mA}$

$I_z=I-I_L=8-5=3mA$