Calculate Inside Painting Area

The inside surface consists of the curved area and the base. $A_{\text{inside}} = 2\pi r H + \pi r^2$.

$A_{\text{inside}} = 2 imes rac{22}{7} imes 7 imes 21 + rac{22}{7} imes 7^2 = 924 + 154 = 1078 \text{ m}^2$

Calculate Inside Cost

Multiply the inside area by the rate of ₹5 per m².

$\text{\text{Cost}}_{\text{inside}} = 1078 imes 5 = 5390$

Calculate Outside Painting Area

The outside includes the base and the curved surface of height $21 - 1 = 20$ m. $A_{\text{outside}} = 2\pi r (20) + \pi r^2$.

$A_{\text{outside}} = 2 imes rac{22}{7} imes 7 imes 20 + 154 = 880 + 154 = 1034 \text{ m}^2$

Calculate Outside Cost

Multiply the outside area by the rate of ₹7 per m².

$\text{\text{Cost}}_{\text{outside}} = 1034 imes 7 = 7238$

Calculate Total Cost

Sum the inside and outside costs.

$\text{\text{Total} \text{Cost}} = 5390 + 7238 = 12628$