Question

Prism M has a length of 2 in, a width of 4 in, and a height of 7 in. If the length, width, and height of Prism N are triple that of Prism M, what is the surface area of Prism N?

Answer 1

The surface area is the combination of all the areas of the faces, or as an easy formula:

Surface Area = 2 [( width x length) + (width x height) + (length x height)]

If you multiply all the sides by 3, they turn out to be:
width = 12 in
height = 21 in
length = 6 in

Now just plug the numbers into the surface area equation:
Surface Area = 2 [(width x length)+(width x height)+(length x height)]
Surface Area = 2 [(12 x 6)+(12 x 21)+(6 x 21)]