$($b$)$ Static pile load test was carried out on a $400mm-$ by $-400mm$ solid concrete pile $($with ${}_{\text{c}\text{o}\text{n}}=4$ksi $)$ installed $20m$ into a loose$-$to$-$medium sandy soil. The pile was driven into the soil. Selected load displacement data are shown in the table below. $($a$)$ determine the allowable load if the serviceability limit is $12mm.($b$)$ Is the maximum load the ultimate load? Justify your answer. $($c$)$ estimate the structural capacity of the tested pile.

$\backslash$table$[[$Load $($ton$),0,24,50,75,100,125,150,175,191,195,175],[$Displacement $(mm),0,0\mathrm{.}3,0\mathrm{.}85,1\mathrm{.}21,1\mathrm{.}85,2\mathrm{.}72,3\mathrm{.}93,5\mathrm{.}67,13\mathrm{.}54,24\mathrm{.}7,24\mathrm{.}1]]$