What is the psi at a point 15 ft above the bottom of a lake that is 367 ft deep?

• A. 158 psi
• B. 152 psi
• C. 144 psi
• D. 164 psi

Answer: (B)

Pressure from a lake increases with depth because the water column above adds weight. To find the pressure at a point 15 ft above the bottom, first get how deep it is below the surface: 367 ft total depth minus 15 ft above the bottom equals 352 ft deep. Freshwater pressure is about 0.433 psi per foot of depth, so 352 ft × 0.433 psi/ft ≈ 152 psi. Therefore the pressure at that point is about 152 psi.