The following surface height data is measured using a profilometer: X, X, X, in mm. Calculate the the kurtosis. Use the average as the reference height. Zi = Z'i - average of the heights Ra=sqrt(1/N*sum(z;)?) for i=1 to N Risk=1/Rq3 *1/N* sum(zi) for i=1 to N Rku=1/R.4*1/N*sum(z;)4 for i=1 to N