Final answer:
Greg will need D) 37.5 square inches of poster board to make a cubical box with an edge length of 2.5 inches, as calculated by substituting the edge length into the surface area formula A=6x².
Step-by-step explanation:
The question you're asking about relates to finding the surface area of a cube. In this case, Greg wants to make a cubical box with an edge length of 2.5 inches. The surface area A of a cube with edge length x is calculated by the formula A = 6x².
To find out how much poster board Greg will need, we can substitute x with 2.5 inches into the formula:
A = 6 x (2.5 inches)²
A = 6 x (6.25 inches²)
A = 37.5 square inches
So, Greg will need 37.5 square inches of poster board to create the box, which corresponds to answer option D.