General Aptitude TestQuantitative ReasoningMensuration: 2D/3D

If the curved surface area of a solid cylinder is one-third of its to…

If the curved surface area of a solid cylinder is one-third of its total surface area, then what is the ratio of the diameter to the height?

Answer & explanation

Correct answer: option 3

C.S.A. = 2\(\pi \)rh

T.S.A. = C.S.A. + 2\(\pi \)r²

ATQ,

T.S.A. : C.S.A. = 3 : 1

C.S.A. + 2\(\pi \)r² : C.S.A. = 3 :1

⇒ 2\(\pi \)r² : 2\(\pi \)rh = 2 : 1 (C.S.A. = 1R)

⇒ r : h = 2 : 1

or 2r : h = 4 : 1

Hence,

Diameter : Height = 4 : 1