We can solve this problem using the formula:
P2 – P1 = ρ g (h2 – h1)
where,
P2 = pressure of the gas manifold = ?
P1 = pressure of the outside air = 754 torr = 100,525 Pa
ρ = density of mercury = 13560 kg/m^3
h2 = height in gas manifold = 76.2 cm = 0.762 m
h1 = height in air = 23.8 cm = 0.238 m
So w can directly find for P2:
P2 = 13560 * 9.81 * (0.762 – 0.238) + 100,525
P2 = 170,229.37 Pa
Convert back to torr:
P2 = 170,229.37 Pa = 1276.83 torr (ANSWER)