To find the volume of metal used for the cylindrical pipe, we calculate the volume of the outer cylinder and subtract the volume of the inner cylinder.

 Convert dimensions to consistent units

- Outer diameter = \(7.2 \, \text{cm}\), so outer radius \( R = \frac{7.2}{2} = 3.6 \, \text{cm} \)
- Inner diameter = \(2.8 \, \text{cm}\), so inner radius \( r = \frac{2.8}{2} = 1.4 \, \text{cm} \)
- Height \( h = 1 \, \text{m} = 100 \, \text{cm} \)

 Calculate the volume of the outer cylinder

The formula for the volume of a cylinder is:
\(V = \pi R^2 h\)
For the outer cylinder:
\(V_{\text{outer}} = \pi (3.6^2)(100) = \pi (12.96)(100) = 1296\pi \, \text{cm}^3\)

Calculate the volume of the inner cylinder

For the inner cylinder:
\(V_{\text{inner}} = \pi (1.4^2)(100) = \pi (1.96)(100) = 196\pi \, \text{cm}^3\)

Calculate the volume of metal used

The volume of metal is given by:
\(V_{\text{metal}} = V_{\text{outer}} - V_{\text{inner}} = 1296\pi - 196\pi = 1100\pi \, \text{cm}^3\)

Thus, the volume of metal used for the cylinder is:
1100\(\pi\)cm\(^3\)