A $6\mathrm{.}0-m$ high retaining wall is subjected to a surcharge on the ground surface, as shown in figure. Determine the increase in lateral pressure,

in $k\frac{N}{m},($on the plane of the section shown$)$ at $z=5m$ due to the applied load. $($Note: $z=$ distance measured downwards from the top of the wall.$)$

$Q=75kN$

$0\mathrm{.}47$

$0\mathrm{.}65$

$0\mathrm{.}37$

$0\mathrm{.}79$