Question

the radius and height of a cylinder are in the ratio of 7:2 if the volume of the cylinder is 8316 cm³ find the total surface area of cylinder

Answer 1

Sol:
Let ratio of radius and height of a cylinder are 7x : 2x.

Volume of the cylinder (V) = πr2h

8316 = (22/7)(7x)2(2x)

⇒ 8316 = (22 x 14) x3

⇒ x3 = 8316 / 308

⇒x3 = 27

∴x = 3.

radius of the cylinder = 7 x3 = 21 cm.

height of the cylinder = 2x 3 = 6 cm

Total surface area of the cylinder = 2πr( r + h)

= 2 x (22/7) 21( 21 + 6)

= 2 x 22 x 3 x 27

= 3564 cm2 .