# Find the Ratio of Its Diameter to Its Height :

The curved surface are of a cylindrical pillar is 176 m² and its volume is 616 m³. Find the ratio of its diameter to its height.

- 7:2
- 7:3
- 3:7
- 2:11

Answer is (1) **7:2**

**Explanation:-**

The curved surface area of a cylinder = 2π r h

Then , 2π r h = 176

r h= 176 x 7/22 x 2

r h = 4 x 7

r h = 28 cm

h = 28/r ……………………… (1)

**Formula –
**The volume of a cylinder = π r² h

The, π r² h = 616

r² h = 616 x 7/22

r² h = 28 x 7

r² h = 196 cm

From equation (1), h = 28/r

r² (28/r) = 196

28 r = 196

r = 196 /28

r = 7 cm

diameter = 2 x r

diameter = 2 x 7

= 14 cm

Put the value of r = 7 cm in equation (1),

Then, h = 28/4

h = 4 cm

Then, the ratio of diameter and height = 14/4

7: 2

Hence, the answer is (1) 7: 2.