4. A layer of sand with a depth of 4 m is underlain by a layer of clay. For sand: Specific gravity-2.65 Void ratio=0.60 For clay: Specific gravity=2.70 Void ratio = 0.80 Determine the total stress, pore water pressure and effective stress @ 2 m, 6 m and 10 m below the ground surface: a. Water table 3 m below the ground surface b. Water table 2 m above the ground surface c. Water table 5 m below the ground surface