1. The problem statement, all variables and given/known data Imagine a system, in contact with a heat reservoir, with three particles. Each particle may be in a state of energy 0 or ε. What's the temperature of the reservoir such that the mean energy of the system, <E>, is 1.2ε? 2. Relevant equations 3. The attempt at a solution I tried using the formula: S = Kb ln(Ω(E)) dS/dE = Kb / Ω(E) = 1/T However I don't think this is the right way to go. Since I only know the average value of the energy I don't think I can find the temperature of the system! Any hints would be highly appreciated! Thanks.