Subject: General Aptitude · Chapter: Area · Exam: · Marks: · Difficulty:
There is a rectangular tank of length 180 m and breadth 120 m in a circular field. If the area of the land portion of the field is $40000 \mathrm{m}^{2}$, what is the radius of the field?
(a)130 m
(b)135 m
(c)140 m
(d)145 m
Answer
Answer (as printed): C
Explanation
Total area of the field $=[(180 \times 120)+40000] \mathrm{m}^{2}$ $$=(21600+40000) \mathrm{m}^{2}=61600 \mathrm{m}^{2} . \begin{aligned} \therefore \pi R^{2}=61600 & \Leftrightarrow R^{2}=\left(61600 \times \frac{7}{22}\right)=(400 \times 7 \times 7) \mathrm{m} \\ & \Leftrightarrow R=(20 \times 7) \mathrm{m}=140 \mathrm{m} \end{aligned}$$