A large $7-$cm$-$thick iron plate $($k $=15$ W$/$m$$K$)$ is exposed to an environment at $25\backslash$deg C with a heat transfer coefficient of $100$ W$/$m$2$K$.$ The left surface of the iron plate is insulated. $($a$)$ Express the differential equation in its simplest form and the boundary conditions for steady one$-$dimensional heat conduction through the iron plate without heat generation, and $($b$)$ solve the differential equation to find the temperatures on both surfaces of the iron plate. $($T$($x$=0)=$T$($x$=$L$)=25$oC$)($c$)$ Can we determine the temperature on the plate surfaces using the thermal resistance concept? Why?