Answers

2016-03-13T09:54:54+05:30
Let the original radius be r

so the original volume = 4/3πr³

new radius = 2r

so new volume = 4/3π (2r)³ = 4/3 π (8r³)

ratio = 4/3πr³/4/3π (8r³)
        = r³ / 8r³ = 1/8 

so the ratio is 1:8
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2016-03-13T10:12:57+05:30
Let the radius of 2 sphere  be r and 2r
  
      surface area of original sphere
     ____________________________
        surface area of new sphere
   
    =4πr²
      ____
      4π(2r)²

= 1/4       = 1:4

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