The plan of a flexible rectangular loaded area is shown in the figure below. The uniformly distributed load on the flexible area, $a,$ is $79k\frac{N}{m^2}.$ Determine the increase in the vertical stress, ${}_z($in $k\frac{N}{m^2}),$ at a depth of $z=2m$ below the following. Use this table as needed.

$($a$)$ Point $A$

$1\mathrm{.}1$

$($b$)$ Point B

$$

$k\frac{N}{m^2}$

$($c$)$ Point $C$

$2\mathrm{.}87k\frac{N}{m^2}$