Jordan should use option B: 6 in x 9 in x 6 in prism. Its volume matches the pyramid's, proving the formula.
The answer is the rectangular prism with the dimensions 6 inches by 6 inches by 9 inches. Here's why:
1. Volume formula: The volume of a pyramid is one-third the area of the base times the height. In this case, the area of the base is 6 inches x 6 inches = 36 square inches, and the height is 10.5 inches. Therefore, the volume of the pyramid is (1/3) * 36 sq in * 10.5 in = 126 cubic inches.
2. Prism volume: The volume of a rectangular prism is the length x width x height. We need to find a prism with a volume of 126 cubic inches. Trying out the options:
Option A: 6 inches x 6 inches x 9 inches = 324 cubic inches (too large)
Option B: 6 inches x 9 inches x 6 inches = 126 cubic inches (perfect)
Therefore, the rectangular prism that Jordan should insert the pyramid into is option B, with the dimensions 6 inches by 9 inches by 6 inches. This is because the volume of this prism is equal to the volume of the pyramid, which satisfies the condition for proving the formula.