Question

How many coins of 4 cm in diameter and 3 cm thick to be melted to form a right circular cylinder of height 16 cm and radius 6 cm.
1. 64
2. 34
3. 48
4. 16

Answer 1

Correct Answer - Option 3 : 48

Given:

Diameter of coin = 4 cm

Height of coin = 3 cm

Height of cylinder = 16 cm

Radius of cylinder = 6 cm

Formula Used:

Volume of cylinder = πr²h

Radius =  Diameter/2

Calculation:

Diameter of coin = 4cm

Radius =  Diameter/2

⇒ Radius = 4 cm/2

⇒ Radius = 2 cm

⇒ Volume of coin =  π(2 cm)² × (3 cm)

⇒ Volume of coin = 12π cm³

Volume of cylinder = π(6 cm)2 × (16 cm)

⇒ Volume of cylinder = 576π cm³

Number of coins = Volume of cylinder/Volume of 1 coin

⇒ Number of coins = 576 cm3/12π cm3

⇒ Number of coins = 48

48 coins can be formed.

∴ The correct option is 3 i.e. 48