Find the volume of the prism

Hmm....can you clarify what is 6 m long?

Does the length of a side of the base = 6 m ...or is the 6 m the length of the apothem?

Or does the 6 m stretch from corner to corner on the hexagon?

Or does the 6 m stretch from "wall" to "wall" on the hexagon?

If the length of one side of the base is 6m, then you have the correct answer.

I think you mean the side = 6

The area of the base  =  6 (1/2) 6^2 * √3/2     m^2

The  volume  = 

  base area * height  =

[ 6 (1/2) 3^2 * √3/2 }  * 8   ≈  748.25 m^3

Close enough !!!!