Answering the following question
1000 atoms are in equilibrium at temperature T. Each atom has two energy states, $E_1$ and $E_2$, where $E_2 > E_1$ . On average, there are 200 atoms in the higher energy state and 800 in the lower energy state.
What is the Temperature?
Why is the answer $T = (E_2 - E_1)/(2 k_B ln 2)$, specifically what is $k_B$?
The original question can be found here under Question 3.