$\backslash$table$[[$The following,$],[\backslash$table$[[$U$.$S$.],[$sieve no$.]],\backslash$table$[[$Mass of soil$],[$retained $($g$)]]],[4,0],[10,18\mathrm{.}5],[20,53\mathrm{.}2],[40,90\mathrm{.}5],[60,81\mathrm{.}8],[100,92\mathrm{.}2],[200,58\mathrm{.}5],[$Pan$,26\mathrm{.}5]]$

a$.$ Determine the percent finer than each sieve and plot a grain$-$size distribution curve.

b$.$ Determine $D_{10},D_{30},$ and $D_{60}$ for each soil.

c$.$ Calculate the uniformity coefficient $C_u.$

d$.$ Calculate the coefficient of gradation $C_c.$