Question 20320
Space required by one person = 1000 CF
Space required by 280,000,000 peopel  = 280,000,000,000 CF

Let the radius of the spher is r
so volume of the sphere = Pi*r^3
volume of people should be equal to the volume of sphere

so   Pi*r^3 = 280,000,000,000
        r^3 = 280,000,000,000/3.14
        r^3 = (280/3.14)* 1000,000,000
        r^3 = 89*1000,000,000
        r = (89 * 1000,000,000)^1/3
          = (89)^1/3 * 1000
        r = 4.4 * 1000 Feet
 
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