Using the volume of the spherical balloon, it is found that it will take 24 hours for the balloon to become completely empty.
The volume of a sphere of radius r is given by:
[tex]V = \frac{4\pi r^3}{3}[/tex]
Aspherical balloon has a radius of 6 feet, hence the volume is:
[tex]V = \frac{4\pi 6^3}{3} = 905[/tex]
It has already lost 20% of it's air, and air is leaking out of the balloon at a rate of 30 cubic feet per minute, hence the volume after t minutes is given by:
[tex]V(t) = 0.8(905) - 30t[/tex]
[tex]V(t) = 724 - 30t[/tex]
It will be completely empty when:
[tex]V(t) = 0[/tex]
[tex]724 - 30t = 0[/tex]
[tex]30t = 724[/tex]
[tex]t = \frac{724}{30}[/tex]
[tex]t = 24.1[/tex]
Rounding, it will take 24 hours for the balloon to become completely empty.
More can be learned about the volume of a sphere at https://brainly.com/question/25608353