Using numerical differentiation please!!

construction, walls are given "R-values", from R10 to above R60. Engineers quantify this effect more specifically using thermal conductivity. Thermal conductivity is defined by Fourier's Law: q=kdxdT Here, q is the heat flux (in W/m2 ), k is the thermal conductivity (in W/mK ), and dT/dx is the temperature gradient through the wall (in K/m ). We wish to estimate the thermal conductivity of a wall by measuring the temperature at various points throughout the wall. Given the heat flux through the wall is 60W/m2 at x=0, and given the following temperature measurements, estimate the thermal conductivity using the most accurate method possible