Data :- $E_F$-E=0.012eV , T = 27℃ = 300K

$K = 1.38 ×10^{(-23)} J/K = (1.38×10^{(-23)})/(1.6×10^{(-19)} ) = 86.25× 10^{(-6)} eV/K$

Formula :- $f(E_C)= 1/(1+e^{((E_C-E_F)/kT)} )$

Calculations :- Total probability = 1

Probability of occupying an energy state + Probability of not occupying the energy state = 1.

f(E) + Probability of not occupying the energy state = 1

Probability of not occupying the energy state = 1- f(E)

Here $f(E) = 1/(1+e^{((E-E_F)/kT)} ) = 1/(1+e^{((0.012/86.25×10^{(-6)}×300))} ) = 0.386$

Hence, 1- f(E) = 1-0.386 = 0.614

Answer :- Probability of not occupying = 0.614