Question

How many coins each of radius 0.25 cm and thickness 0.4 cm, to be melted to make a right circular cylinder of height 4 cm and base radius 10 cm? 
1. 15000
2. 14000
3. 12000
4. 16000

Answer 1

Correct Answer - Option 4 : 16000

Given:

Radius of coin = 0.25 cm

Thickness of coin = 0.4 cm

Height of cylinder = 4 cm

Radius of cylinder = 10 cm

Formula Used:

Volume of cylinder = πr²h

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

Calculation:

Volume of coin = 22/7 × (0.25)² × (0.4) cm³

Volume of cylinder = 22/7 × (10)² × (4) cm³

Number of coins = [22/7 × (10)2 × (4)]/[22/7 × (0.25)2 × (0.4)]

⇒ Number of coins = 16,000

∴ 16,000 coins to be melted.

The correct option is 4 i.e. 16,000