4. A smooth vertical wall 4 m high is pushed against an overconsolidated clay (19 kN/m', c 3 kPa, -30, and average su120 kPa). The water table is 1 m below the ground surface. The surface of the overconsolidated clay carries a uniform load of 25 kPa. Using the Rankine theory calculate the resultant force against the wall and the distance from the base of the wall to the resultant force.