the ratio between the radius of base and height a cylinder is2..., Area & Volume, General Mathematics

Question:The ratio between the radius of the base and the height  of a cylinder is`2 : 3.` If its volume is `12936` cu, the total surface area of cylinder is :

A `3080 cm^2` 
B `38808 cm^2` 
C `25872 cm^2` 
D `2587.2 cm^2`

/113

+ AnswerA

+ ExplanationLet radius`= 2x & height`= 3x. Then,

`22/7 xx (2x)^2 xx 3x`

`= 12936 or x^3`

`= (12936 xx 7/22 xx 1/12)`

`= 343 = 7^3`

`:. x = 7.`

So,ratius

`= 14 cm` & height = 21 cm.

:. Total surface area 

`= (2 xx 22/7 xx 14 xx 21 + 2 xx 22/7 xx 14 xx 14)sq.` cm.`

`= 3080 cm^2.`

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