the percentange increase in the surface area of a cube when each..., Area & Volume, General Mathematics

Question:The percentange increase in the surface area of a cube when each side is doubled, is :

A `25%` 
B `50%` 
C `150%` 
D `300%`

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+ AnswerD

+ ExplanationLet the edge of the cube be a. Then, new edge`= 2a`.

Original surface area`= 6a^2,`

New surface area 

`= 6 xx (2a)^2`

`= 24a.^2`

:. Increase in surface area

`= ((18a^2)/(6a^2) xx 100)%`

`= 300%.`

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