the radius of a sphere is increased by 50 increase in..., Percentage, General Mathematics

Question:The radius of a sphere is increased by `50%`. The increase in surface area of the sphere is :

A `100%` 
B `125%` 
C `150%` 
D `200%`

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+ AnswerB

+ ExplanationLet original radius`= R, New radius 

`= 150/100 R`

`= 3/2 R.`

Original Surface area

`= 4 π R^2`

New surface area 

`= 4 π (3/2 R)^2`

`= 9 π R^2`

:. Increase`= ((5 π R^2)/(4 π R^2) xx 100)%`

`= 125%.`

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