The area of the shaded region is equal to the area of the circle minus the area of the square, let's rember the formula to calculate the area of these figures:
Remember that d is the diameter and l is the square length, then, let's apply these formulas:
The diameter is 3.1 ft and the length is 2.5 ft, then
Therefore, the area of the shaded region is 1.3 ft^2.