a$)$ A $09-$pile group $($diameter of pile $=400mm$; length $=10m$ is installed in a layered cohesive soil with the following properties: Upper layer: cohesion $=75$kPa; adhesion factor $=0\mathrm{.}5$; unit$-$weight of soil $=18k\frac{N}{m^3}$; Thickness $=6m.$

Lower layer, cohesion $=155$kPa; adhesion factor $=0\mathrm{.}45$; unit weight of soil $=21k\frac{N}{m^3}.$ Determine the safe load carrying capacity of the pile group, assume any missing data.