Question

The number of coins of radius $0.75cm$ and thickness $0.2cm$ are to be melted to make a right circular cylinder of height $8cm$ and base radius $3cm$ is

• A. $460$
• B. $500$
• C. $600$
• D. $640$

Answer 1

Answer: (D)

$640$

Number of coins $=\frac{\text{Volume of the cylinder}}{\text{Volume of one coin}}$ $=\frac{\pi \times 3\times 3\times 8}{\pi \times 0.75\times 0.75\times 0.2}=640$