Answer:
1) P = rho g h = d g h where d is replacing the greek letter rho (density)
a) pressure at A must be 1/2 that of B because of 1/2 the height
b) pressure at B equals that at D because the height is the same
(Pascal's principle - pressure in a fluid is same in all directions)
c) pressure A is the same as that C
d) the pressure at B would be .8 of the water at B if paraffin replaced the water (P = d g h = .8 * dw g h) due to change in density
2) Volume = 4 m X 3 m X 2 m) = 24 m^3 volume of tank
b) mass = volume * density = 24 m^3 * 800 kg / m^3 = 19,200 kg
c) weight = mass * gravity = 19,200 kg * 9.8 m/s^2 = 188,160 Newton's
d) P = d g h = 800 kg/m^3 * 9.8 m/s^2 * 2 m 15,680 N/m^2
Pressure is given in force/area or N/m^2
3) Pw / Pp = dw / dp = 1000 / 800 = 1.25
Pw = 1.25 Pp = 15,680 m/s^2 * 1.25 = 19,600 Pascal's