What temperature $($in $\backslash$deg C$)$ is required to obtain $0\mathrm{.}50\%$ C at a distance of $1\mathrm{.}4$ mm beneath the surface of a $0\mathrm{.}20\%$ C steel in $2$ h$,$ when $1\mathrm{.}10\%$ C is present at the surface? Assume that the iron is FCC$.$ Use the table below for error function values as needed.