Question

A rectangle plot of land measures $45$ m $\times$ $30$ m. A boundary wall of height $2.4$ m is built all round the plot at a distance of $1$ m from the plot. Find the area of the inner surface of the boundary wall.

• A. $226.2m^2$
• B. $457.2m^2$
• C. $379.2m^2$
• D. $291.2m^2$

Answer 1

The correct option is C $379.2m^2$

Given, a plot of dimension $45$ m $\times 30$ m.

A boundary wall of height $2.4$ has to be built all round the plot at distance $1$ m from the plot.
Since boundary wall has to be made $1$ m away from plot.

So, there will be $1$ m increase in length on both sides and $1$ m increase in breadth on both sides.
So, new length $=45+1+1=47$ m
New breadth $=30+1+1=32$ m
Total area of boundary $=$ lateral surface area of cuboid
$=2h(l+b)=2\times 2.4\times (47+32)=379.2m^2$