ABC26GN4589 · Area
Subject: General Aptitude · Chapter: Area · Exam: · Marks: · Difficulty:
The areas of two concentric circles forming a ring are 154 sq. cm and 616 sq. cm. The breadth of the ring is
(a)7 cm
(b)14 cm
(c)21 cm
(d)28 cm
Answer
Explanation
$\pi R_{1}^{2}=616 \Leftrightarrow R_{1}^{2}=\left(616 \times \frac{7}{22}\right)=196 \Leftrightarrow R_{1}=14 \mathrm{cm}$. $$\pi R_{2}^{2}=154 \Leftrightarrow R_{2}^{2}=\left(154 \times \frac{7}{22}\right)=49 \Leftrightarrow R_{2}=7 \mathrm{cm} .$$ Breadth of the ring $=\left(R_{1}-R_{2}\right) \mathrm{cm}=(14-7) \mathrm{cm}=7 \mathrm{cm}$.
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