Question

If the ratio of the curved surface area and volume of a right circular cylinder is 5 ∶ 7, then its radius is:
1. 2.6 unit
2. 2.8 unit
3. 3.8 unit
4. 3.2 unit

Answer 1

Correct Answer - Option 2 : 2.8 unit

Given:

Ratio of the curved surface area and volume of a right circular cylinder =  5 ∶ 7

Formulas used:

Curved surface area of cylinder = 2πrh 

Volume of the cylinder = πr²h

Calculation:

2πrh/πr2h = 5/7 

⇒ 2/r = 5/7 

⇒ 2/r = 5/7

⇒ r = 14/5 = 2.8 units 

∴ The radius of the cylinder is 2.8 units.