Curved Surface Area Solution3





In this page curved surface area solution3 we are going to see solution of some practice questions.

Question 6

The total surface area of a solid right circular cylinder is 1540 cm². If the height is four times the radius of the base, then find the height of the cylinder.

Solution:

Total surface area of cylinder = 1540 cm²

                     2 Π r (h + r) = 1540

                               h = 4 x radius of the base

                                       h = 4 r

                     2 Π r (4 r + r) = 1540                        

                     2 Π r (5 r) = 1540                        

  2 x (22/7) x 5 r² = 1540

                          = 1540 x (1/2) x (7/22) x (1/5)

                          = (1540 x 7)/(2 x 22 x 5)

                          = (1540 x 7)/(2 x 22 x 5)

                      r² = 49

                      r = √7x 7

                      r = 7 cm

                   height  = 4 (7)

                               = 28 cm

Height of the cylinder = 28 cm


Question 7

The radii of two right circular cylinders are in the ratio 3:2 and their heights are in the ratio 5:3. Find the ratio of their curved surface areas.

Solution:

Let r₁ , r₂ and h₁ , h₂ are radii and heights of first and second cylinders respectively.

Now we have to find the ratio of their curved surface areas

Curved surface area of cylinder = 2 Π r h

Curved surface area of first cylinder = 2 Π r₁ h₁

Curved surface area of first cylinder = 2 Π r₂ h₂

r₁ : r₂ = 3 : 2

r₁/r₂ = 3/2

r₁= 3r₂/2

h₁ : h₂ = 5 : 3

h₁/h₂ = 5/3

h₁= 5h₂/3

 Ratios of curved surface area of two cylinders

           2 Π r₁ h₁  :   2 Π r₂ h₂

            (3r₂/2) (5h₂/3) :  r₂ h₂

                      5/2 : 1

                          5 : 2

curved surface area solution3 curved surface area solution3