Question

There is a rectangular tank of length $180m$ and breadth $120m$ in a circular field, if the area of the land portion of the field is $40000m^2$, what is the radius of the field?

• A. $130m$
• B. $135m$
• C. $140m$
• D. $145m$

Answer 1

The correct option is C $140m$

Length of tank $=180m$

Breadth of tank $=120m$

Area of tank

$=l\times b=180\times 120=21600m^2$

Area of land portion $=40000m^2$

Therefore,

Area of circular field $=40000+21600=61600m^2$

Let $r$ be the radius of a circular field.

Therefore,

Area of field $=\pi r^2$

$\Rightarrow \pi r^2=61600$

$\Rightarrow r^2=\frac{61600\times 7}{22}$

$\Rightarrow r=\sqrt{19600}=140m$

Hence the radius of field is $140m$.