1. The problem statement, all variables and given/known data A homicide victim is found to have a temperature of 31°C at the stroke of midnight. At 1:00AM his temperature dropped to 29°C. Assuming that the temperature of the room stays at 20°C, when did the murder take place? 2. Relevant equations - 3. The attempt at a solution This is more of a problem in how to solve for the constants and variables instead of setting up the problem. By noticing that: dT/dt = -k(T-N) (where N is the lowest temperature value and T the temperature) We obtain a solution to the differential equation which is shown below: T(t) = 20 + (T0 - 20)e-kt And with this result, we can label the time 12.00AM as h and 1.00AM as h+1: T(h) = 20 + (T0-20)e-kt = 31 T(h+1) = 20 + (T0-20)e-k(t+1) = 29 With clearing these two expressions (dividing them), we obtain that the value of the constant k is: k ≈ 0.2007 However, now I can't work out anything else with having the value of the constant. I can't clear neither for T0 (the temperature at the beginning) nor k (the constant). I've dealt with a similar problem but in this case the initial temperature was given so the problem could be worked out. However, how can we proceed in this case?