Originally Posted by

**Chris L T521** Direct integration and Separation of variables is usually taught in high school calculus (I know that's the case in the US but I'm not sure what its like for other countries). As a result, they "should" know how to solve cooling problems using separation of variables along with given initial conditions.

If you can't use separation of variables, then you'll have to assume that the equation for temperature is $\displaystyle T(t)=S+T_0e^{-kt}$, where $\displaystyle T_0$ is the initial temperature and $\displaystyle S$ is the surrounding temperature.