This is not answerable. The pressure at the bottom of the pool depends on the height of the pool only!
Pbottom = Patm + ρgh English units are a pain. It's easier to do in metric and then convert.
3 meter pool height (depth) PB = 1.013 x 105 Pa + (1000 kg/m3)(9.8 m/s2)(3m) =130700 Pa
130700 Pa (14.7 psi/101300 Pa) =19.0 psi (note that it's about 10 meter depth per atmosphere increase in pressure.
Hope that helps. Take care.
JACQUES D.
tutor
I made it up as an example. Also, little information is given, so I had to assume that the aperture is small and the pool area is large... Approximately static pressure.
Report
07/21/22
Grigoriy S.
tutor
Thanks. I believe that the problem is incorrect from the very beginning. Hydrostatic pressure is just product of density, acceleration of free fall and height of the water in the pool. But when the drain is open, we are talking about the fluid in motion, hence about the gauge pressure of moving fluid.
Report
07/22/22
Grigoriy S.
07/21/22