Mathematics
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.
Answer
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.
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