Question 494251
Measure the circumference with a tape (or look up the dimensions on the web somewhere).
The radius is the circumference/(2pi) (get it in centimeters)
{{{Vol = 4*pi*r^3/3}}} cubic cms
1 liter = 1000 cc
{{{Vol = 4*pi*r^3/3000}}} liters
-------------------
That's the volume of the ball and the air inside the ball.