$4\mathrm{.}25$ Aa soil has a liquit limmit of $61$ and a plastic limit of $30.$ A moister content test performed on a undisterbed sample of this soil yielded the following results:

mass of soil$+$ can before placing in oven $96\mathrm{.}20$g

Mass of soil$+$ can afterremoval from the oven$71\mathrm{.}90$g

mass of can $20\mathrm{.}80$g

compute the following:

a the plasticity index

bthe moister content

c the liquidity index