Answer:
If we assume that the box is a cube with 150 m² surface area
Area of 1 face = 150 m² / 6 = 25 m²
The box will exert a downward force of
Force = mass * acceleration due to gravity
Force = 300 kg * 9.81 m/s² N
Force = 2943 N
The box exerts a pressure ( force / unit area) = 2943 N / 25 m²
Pressure = 117.7 N/m²
Thank you, if you found this helpful please comment.