Explanation:
it means the shape of the balloon is close to a sphere.
the volume of a sphere is
4×pi×r³
so, it bases on r³.
that means any scaling factor f between 2 similar balloons for the radius has to be multiplied in 3 times (once for every "r").
in our case we know
8.4 = 2.8 × f
f = 8.4 / 2.8 = 3
so,
large volume = small volume × f×f×f =
= small volume × f³ = 92×3³ = 92×27 =
= 2,484 cm³