$[10]10$ points

$($a$)$ Determine the air pressure in the tank

$($pressure at point $1,P_1).$

Given,

$h_1=0\mathrm{.}10m.$

$h_2=0\mathrm{.}20m.$

$h_3=0\mathrm{.}35m$

${}_w=1000\frac{kg}{m^3}$;

${}_{\text{o}\text{i}\text{l}}=850\frac{kg}{m^3}$;

${}_{\text{m}\text{e}\text{r}\text{c}\text{u}\text{r}\text{y}}=1030\frac{kg}{m^3}$

$($b$)$ Determine what the differential fluid

height $h_3$ would be for the same air

pressure if the mercury in the last column

were replaced by seawater?