From tables, Silver has a resistivity of 1.6*10^-8 ohm-m at 20 deg.C, and it increases by 0.0038 ohm-m per deg.K increase. Therefore if the temperature rise above 20 deg.C is T, then silver will have resistivity of 1.6*10^-8(1 + 0.0038T) ohm-m
At room temperature, the resistivity of tungsten (from tables) is 5.6*10^-8.
The resistivity of silver will be 4 times that of tungsten (at room temperature) when 1.6*10^-8(1 + 0.0038T) = 4*5.6*10^-8 1 + 0.0038T = 14 T = 13/.0038 = 3421 deg.K approx
