4.1 During Atterberg limit tests in the soil mechanics laboratory, the students obtained the following results from a clayey soil. Liquid limit tests: Number of Moisture blows, N content (%) 14 38.4 16 36.5 20 20 33.1 28 27.0 Plastic limit tests: Students conducted two trials and found that PL = 17.2% for the first trial and PL = 17.8% for the second trial. a. Draw the flow curve and obtain the liquid limit. b. What is the plasticity index of the soil? Use an average value of PL from the two plastic limit trails. 4.2 Refer to the soil in Problem 4.1. A second group of students conducted only one test and found that the groove on the soil sample closed 12.5 mm when 30.4%. Estimate the liquid limit by the one-point method. N=21 and w=