The level of water in a city water tower is 125ft. above the ground. The tank is kept with an air space which can be pressurized with compressed air. It is important to maintain a pressure at the bottom of the tower at 75 psig. What gauge pressure has to be applied to the air in the top of the tower to get the required pressure at the bottom of the tower. If the atmospheric pressure is 755mmHg, what is the absolute pressure at the bottom of the tower. Draw the system and show the pressure gauges.