A cylinder 84 cm long is made of steel. Its external and internal diameters are 10 cm and 8 cm respectively. What is the volume of the steel in the cylinder (in $10^{-3}m^3$ and correct up to three decimal places)?

2.376

We know that,

Volume of the cylinder = π (R² - r²)h

We have,

Height of the cylinder = 84 cm

External diameter = 10 cm

then, External radius of the cylinder = 5 cm

Internal diameter = 8 cm

then, Internal radius of the cylinder = 4 cm

As we know,

 $\frac{22}{7}$ × (5² - 4²) × 84 cm³= 22 × 9 × 12  = 2376 cm³ or 2.376 × 10^-3 m³

Answer = 2.376