Problem $2.$ The water in the tank shown below is pressurized using an air pad $($Air is pumped into the tank until desired pressure is reached. A multi$-$fluid manometer is used to measure the pressure of the air. Take

$h_1=\mathrm{.}15m,h_2=\mathrm{.}3m,h_3=\mathrm{.}6m$; the density of water is $1000k\frac{g}{m^3},$ oil is $800k\frac{g}{m^3},$ and mercury is $13,600k\frac{g}{m^3}$; height of water in the tank is $1\mathrm{.}5$ m $,$ The outside air pressure is $100$ kPa $.$

a$)$ If the system was taken as the volume of just the tank, is it an open or closed system?

b$)$ If the system was taken as all the water is it an open or closed system?

c$)$ Determine the gage pressure in the air at point $1.$

d$)$Determine the absolute pressure of the water at the bottom of the tank.