Area and Perimeter Practice Test 1

Question : 14 of 40

Marks: +1, -0

The areas of two concentric circles, forming a ring, are 154 sq. cm and 616 sq. cm. respectively. The width of the ring is

Solution:

Here,

πR^2

= 616 and

πr^2

= 154
Since

πR^2

= 616
⇒

R^2

{616×7}/{22}

⇒

R^2

= 196
∴ R = 14 cm

Now, and

πr62

= 154
⇒

r^2

{154×7}/{22}

∴ r = 7 cm
∴ Width of the ring = 14 – 7 = 7 cm.

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