A project engineer is planning to get the soils from an offsite borrow pit in order to use themas subgrade materials for the roadway pavement. The following laboratory test results for Atterberg limits and sieve$-$analysis were obtained for the soil sample from the offsite borrowpit. $[5$ points$]$Sieve analysisSieve size Percent passing by weightNo. $8(2\mathrm{.}36$ mm$)100$No$.16(1\mathrm{.}18$ mm$)99\mathrm{.}3$No$.40(0\mathrm{.}425$ mm$)97\mathrm{.}9$No$.60(0\mathrm{.}250$ mm$)93\mathrm{.}1$No$.100(0\mathrm{.}150$ mm$)77\mathrm{.}2$No$.200(0\mathrm{.}075$ mm$)58\mathrm{.}6$Atterberg limitsLiquid limit $($LL$)29$Plastic limit $($PL$)19($a$)$ Classify this soil according to AASHTO system including the group index. Show how you arrive at the final classification.$($b$)$ According to AASHTO system, is this soil excellent to be used as subgrade materials?