$($a$)$ Calculate the absolute pressure at the bottom of a fresh$-$water lake at a depth of $27\mathrm{.}6$ m$.$ Assume the density of the water is $1\mathrm{.}00103$ kg$/$m$3$ and the air above is at a pressure of $101\mathrm{.}3$ kPa.

Pa

$($b$)$ What force is exerted by the water on the window of an underwater vehicle at this depth if the window is circular and has a diameter of $42\mathrm{.}0$ cm$?$

N