1. **State the problem:** Find the lateral surface area of a square pyramid with base edge length 6 ft and slant height 11 ft. 2. **Formula:** The lateral surface area (LSA) of a square pyramid is given by $$\text{LSA} = \frac{1}{2} \times \text{Perimeter of base} \times \text{Slant height}$$ where the perimeter of the base is the sum of all four sides of the square. 3. **Calculate the perimeter of the base:** $$\text{Perimeter} = 4 \times 6 = 24 \text{ ft}$$ 4. **Apply the formula:** $$\text{LSA} = \frac{1}{2} \times 24 \times 11$$ 5. **Simplify:** $$\text{LSA} = 12 \times 11 = 132 \text{ ft}^2$$ 6. **Round the answer:** The lateral surface area is already a whole number, so $$\boxed{132} \text{ ft}^2$$ This is the lateral surface area of the pyramid.