In a shell and tube heat exchanger you know that the thermal conductivity of its material at $6\backslash$deg C is $0\mathrm{.}035$W$/$m $\backslash$deg C and at $160\backslash$deg C it is $2\mathrm{.}867$ W$/$m $\backslash$deg C$.$

If the exchanger operates between $44\backslash$deg C and $71\backslash$deg C$,$ what would be the average conductivity of the material in W$/$m $\backslash$deg C$?$