Problem $3$:

Classify the $6$ soils described in the attached two plots of Fig. P$3-6($plots $(1)$ and $(2)$ from Holtz and Kovacs $1981).$ Use the Unified Soil Classification System. List the values for the ${10}^{th},{30}^{th},$ and ${60}^{th}$ percentile equivalent grain size diameters, and compute the coefficients of uniformity and curvature only if required for classification purposes $($hint: they are not always needed$).$