Each edge of a cube is increased by 50%. How do you find the percentage of increase in the surface area of the cube?

1 Answer
May 5, 2016

Remember that the formula for the surface area of a cube is 6s2

This is because we find the area of one side s2, then multiply it by the number of sides a cube has, which is 6.

So, if we increase the edge length of a cube, instead of s, we are going to have 1.5s Think about it. We have 1s originally, then increasing by 50% of 1 is 0.5, so we have 1.5s

We just plug this in for the surface area formula

6(1.5s)2 = 13.5s2

We want to calculate the percentage of increase, so we put this new surface area over the original surface area.

13.5s26s2

We simplify this, and we get 2.25

This is in decimal format, we move over the decimal to get 225%

We can choose a random side length to check our answer:

I chose s=8, which gave 384 as the original surface area, 864 as the surface area of 12 (8 with a 50% increase)

We multiply 384 by 2.25 and we get 864.