Question

A 4m long wire has a diametee of 0.3 mm if its resistance is 30 ohm find the resistivity and conductivity​

Answer 1

Use the formula

Resistance = Resistivity * Length / Area

So,
Resistivity = Resistance * Area/Length

and for conductivity

Conductivity = 1/Resistivity
Put all the values in Standard units.

Length = 4m
Diameter = 0.3 mm = 3*10^-4 m
Radius = 1.5*10^-4 m
Area = π (1.5*10^-4)^2
Resistance = 30 ohm

Put these values and you'll have your answer !
Hope this helps you !