problem 14

In a problem dealing with a box or cylinder with no top, does the surface area include the interior of the object? For example, in question 14 of the practice test, would the formula for surface area include the inside of the box as well as the outside? It seems like logically the material used would only include the surface of the outside, but last time i asked a question about a problem like this someone said that the interior would be included as well, so i'm sort of confused.