A U-shaped tube is connected to a box at one end and open to the air at the other end. The box is full of gas at pressure , and the tube is filled with mercury of density 1.36×104 . When the liquid in the tube reaches static equilibrium, the mercury column is = 15.5 high in the left arm and = 6.00 high in the right arm, as shown in the figure. What is the gas pressure inside the box?