Use Boussinesq's method to: a. (8 pts) Calculate the total vertical stress (total ozz) in a soil mass at a depth of 5 m vertically below a point load of 6,000 kN, which is applied on the soil surface. The total unit weight of soil is 23 kN/m. b. (12 pts) Plot the variation of vertical induced stress (AG, or AG) due to this point load versus radial distance from the load ("r" ranging from 0 to 10 m; where r = (x + y)05), at a depth of 5 m from the ground surface (z = constant = 5 m). Please use Microsoft Excel or equivalent to obtain this plot. Please also include a table showing values of r (at 1 meter increments), R, r/zf, and Aoz in kPa.