Question

if each edge of a cube is increased by 50/, what is the percentage increase in surface area?

Answer 1

Let the edge of cube was k.

Then ,surface area of this cube was 6k².

If we increase each edge by 50% it will become k+ k(50/100)=k+k/2=3k/2.

Now the surface area of this cube with increased edges will be

6(3k/2)² =54k²/4

=27k²/2

This is the new surface area .Before calculating percentage increase ,we need to find how much percent it is from previous surface area.

$\frac{27k^{2}/2 }{6k^2} 100\\=\frac{27}{12} 100\\=900/4\\=225%$

So it means ,the new surface area is 225% of new (or 100%).

So increase is 225-100 =125%