How do I solve this numerical??
Find the ratio of their resistances. Use the diameter to find the ratio of the area of cross-section.
As they are in series so the current through both of them will be same.
Hence using ohm's law write V1 = I R1 and V2 = I R2.
you can see that the ratio of the p.d. across them will be equal to the ratio of the resistance R1 and R2.