# If the radius of the sphere is doubled, Find the ratio of volume of the new sphere to the original sphere.

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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

surface area of original sphere

____________________________

surface area of new sphere

=4πr²

____

4π(2r)²

= 1/4 = 1:4