TH$3$: Heat transfers by conduction through a cast iron pan. If the hot end is at a temperature of $400$ K and the cool end is at $300$ K $,$ the cross$-$sectional area of the pan is $0\mathrm{.}03m^2,$ the depth of the pan is $1\mathrm{.}8$ mm $,$ and the thermal conductivity of iron is $72\frac{W}{m}$ K $,$ what is the rate of heat transfer through the pan, in W $?$