Question

The walls, ceiling and floor of a cubic room need to be painted. The edge length for the cube is 3 meters. What is the total surface area that will be painted in the room? 27 m² 30 m² 36 m² 54 m²
Please help :D

Answer 1

Each surface has area = 3*3 = 9 m^2
As there are 6 surfaces te total area = 6*9 = 54 m^2 answer.

Answer 2

Since it is a 3-dimensional square (cube), the edge length (L) is essentially the length, width, and height. Any cube has 6 faces (4 sides/walls, a top/ceiling, and a bottom/floor). Volumes (V) and Surface Areas (SA) of cubes are quite simple:
$V = {L}^{3} \\ where \: L = a \: side \: or \: edge \\ SA = one \: face \times 6 \: faces \\ where \: each \: face = L \times L \: or \: {L}^{2}$
therefore since L = 3m, then:
$SA = 6 \times {L}^{2} = 6 \: ({3})^{2} = 6 \: (9) \\ SA = 54 \: {m}^{2}$