Question

Find the ratio between the total surface area of a cylinder to its curved surface area , given that its height and radius are 7.5 cm and 3.5 cm respectively.

Answer 1

      Given radius = 3.5cm   height = 7.5cm   Curved Surface Area of cylinder = 2πrh   = 2*22/7 *3.5 *7.5   = 165 cm2   Total Surface Area of cylinder = 2πr(h+r)   = 2 *22/7 * 3.5(3.5+7.5)   = 242cm2   Ratio of Total Surface Area of cylinder : Ratio of Curved Surface Area of cylinder   = 242 : 165   = 22 :15  

Answer 2

given :-

height of the cylinder = 7.5cm

radius of the cylinder = 3.5cm

formula for finding the CSA (curved surface area) of a cylinder is 2πrh

therefore CSA of the cylinder = 2 × 22/7 × 3.5 × 7.5

= 330/2

= 165cm²

formula for finding the TSA (total surface area) of a cylinder is 2πr(h + r)

therefore TSA of the cylinder = 2πr( h + r )

= 2 × 22/7 × 3.5 ( 7.5 + 3.5 )

= 44/2 × 11

= 484/2

= 242cm²

ratio between the CSA and TSA of the cylinder :-

==> 165 : 242

dividing both 165 and 242 by 11 we get

==> 15 : 22

hence, the ratio between TSA to it's CSA is 22 : 15 or 15 : 22

HOPE THIS HELPS..!!