<u>Explanation:</u>
Determine the weight of footing
Where 
is the weight of footing, γ is the unit weight of concrete, L is the length of footing is the width of footing, and D is the depth of footing
Substitute 
for γ in the equation
Therefore, the weight of the footing is 35.4 kN
Determine the initial vertical effective stress.
Here, 
is initial vertical stress at a depth below ground surface γ is the unit weight of soil, D is depth and u is pore water pressure.
Substitute 
for u in the equation
Therefore, the initial vertical stress is 36 kPa
Determine the vertical effective stress.
Here, is initial vertical stress at a depth below ground surface γ is the unit weight of soil, D is depth and u is pore water pressure.
Substitute 
in the equation.
Therefore, the vertical stress at a depth below the ground surface is
9 kPa
Determine the influence factor at the midpoint of soil layer,
Here 
is the influence factor at the midpoint of soil layer is initial vertical stress, is vertical effective stress, and 
is bearing pressure
Substitute 
in the equation
Therefore the influence factor at the midpoint of the soil layer is 0.693
