Question

consider a system of 3 fermions which can occupy any of the four available energy states with equal probablity find entropy of the system.

Answer 1

Entropy of the system is given by, $S = k_Bln\Omega$

where $\Omega$ is the number of the micro-states and $k_B$ is the Boltzmann constant.

Total number of the micro-states are ${4 \choose 3 } = 4$

So entropy will be, $S = k_Bln4 = 2k_Bln2$