A NEGLIGIBLY SMALL current is passed through a wire of length 15 m and of uniform cross-section 60x 10^7 m2 and its resistance is measured to be 50.what is the restivity of the material at the temperature of the experiment.

50 what? 50 ohms?

rho = sp resistivity = R*A/l
A = 60E7 m^2
R = 50 ohms
l = 15 m
Solve for rho