Question

It costs $1.50 to fill a spherical balloon with a radius of 4 inches full of helium.How much should you charge to fill a balloon full of helium with a radius of 9 inches?

Answer 1

It's a rule of three problem, we have this:

$\frac{1.50}{4}=\frac{x}{9}$

We need to clear x:

$x=\frac{1.50}{4}\cdot9=\frac{13.5}{4}=3.375$

You should charge $3.375 to fill a balloon full of helium with a radius of 9 inches.