A rectangular plot of land measures 41 metres in length and 22.5 metres in width. A boundary wall 2 metres high is built all around the plot at a distance of 1.5 m from the plot. Find the inner surface area of the boundary wall.

Let ABCD be the rectangular plot.

Given,

Length of rectangular plot = 41 metres,

Breadth of rectangular plot = 22.5 metres.

Height of boundary wall = 2 metres.

Boundary wall is built at a distance of 1.5 m. It means wall is built on base PQRS.

From figure,

Length of plot PQRS = 41 + 1.5 + 1.5 = 44 m.

Breadth of plot PQRS = 22.5 + 1.5 + 1.5 = 25.5 m.

By formula,

Inner surface area of the boundary wall = 2(l + b) × h

= 2 (44 + 25.5) × 2

= 2 × 69.5 × 2

= 278 m².

Hence, inner surface area of boundary wall = 278 m².