A hollow cylindrical tube 20 cm long is made of iron and its external and internal diameters are 8 cm and 6 cm respectively. The volume of iron used in making the tube is ( = 227 )

Answer: Option C

External radius R = 4 cm
Internal radius r = 3 cm
Volume of iron used = πR²h - πr²h
= πh(R² - r²)
= πh(R + r)(R - r)
= $$\frac{22}{7}$$ × 20 × (4 + 3) × (4 - 3)
= $$\frac{22}{7}$$ × 20 × 7 × 1
= 440 cm³