The temperature coefficient of resistivity of iron is 5.0 x10-3/degrees C; that of carbon is -0.50 x10-3/degrees C. When an iron wire and a carbon rod, each having the same 10 Ω resistance a 20 degress C, are cooled from that temperature to -80 degrees C, the new ratio of the resistance of the carbon rod to the resistance of the iron wire at the lower temperature is