The question, as posed, doesn't make sense. The Bose-Einstein distribution is an equilibrium distribution-since it refers to a temperature, which doesn't make sense when things depend on time.

What it might mean is just a trivial application of the formula for the average occupation number, that depends on two variables, temperature and difference between chemical potential and energy, so what might be expected is to write down the expression, identify the unknown quantities and use the information provided to find their values.

Here it might be that 0.1 eV is the chemical potential. So it's a completely trivial application of the formula to solve for the temperature, given the average number... Big deal...