a)Work out the total surface area of this cuboid (3cm x 4cm x 2cm). b) The cuboid has density 7g/cm^3, what is the mass of the cuboid?

a) The surface area of a 3 dimensional shape is the sum total of the area of each side of the shape. This cuboid is 3x4x2, and so it has 2 sides with area 3x4 = 12, 2 sides with area 4x2 = 8, and 2 sides with area 2x3 = 6.Adding these 6 areas *corresponding to the 6 sides of the cuboid) together, we get (2x12)+(2x8)+(2x6)= 24+16+12= 52So the cuboid has surface area 52cm^2.b)The mass of a 3 dimensional shape is its volume multiplied by its density. So the mass of this cuboid is its volume multiplied by 7 (the given density).The volume of the cuboid is simply 3x4x2=24cm^3 (this is by the definition of volume).And so the mass of the cuboid is 24x7 = 168g