Question

Sarah has two similar rectangular boxes. The dimensions of Box 1 are four times those of Box 2.

How many times greater is the surface area of Box 1 than the surface area of Box 2?

8

64

4

16

Answer 1

16

Explanation:

an area is always calculated by multiplying 2 dimensions.

when changing the dimensions, then the change factors for EACH dimension go into the calculation too.

therefore, when both dimensions of an area are enlarged 4 times, then the area is enlarged 4×4 = 16 times.

this just propagates to the whole surface area of an object, as each individual area of the overall surface area is enlarged by the same factor. and so, the sum of all the individual areas (= altogether the surface area of the object) is also enlarged in total by the same factor.

just think

16×a + 16×b + 16×c ... = 16×(a+b+c+...)

and you understand why.