A bar of Cu of length 75 cm and a steel bar of 125 cm length are joined together end to end. Both the bars are having same diameter of 2 cm. The free ends of the Cu and the steel bars are maintained at $$100^\circ C$$ and $$0^\circ C$$ respectively. The curved surfaces of the bars are thermally insulated, what is the approximate temperature at Cu-steel junction?
(consider conductivity K of $$Cu = 400 J s^{-1} m^{-1} {^\circ C^{-1}}$$ and K for steel $$50 Js^{-1} m^{-1} {^\circ C^{-1}}$$)