Question

The inner and outer circumference of a circular ring is 22 cm and 44 cm respectively. What is the thickness of the ring ?
1. 2.5 cm
2. 1.5 cm
3. 5.5 cm
4. 3.5 cm

Answer 1

Correct Answer - Option 4 : 3.5 cm

The correct answer is 3.5 cm.

• The thickness of the ring is 3.5 cm.

• Circumference of circle is 2 × pi × r

The inner circumference of a circular ring is 22 cm.

So, 2 × pi × r = 22 cm.

⇒ r = \({22 \over 2 pi}\) = 3.5 cm.

The outer circumference of a circular ring is 44 cm.

So, 2 × pi × r = 44 cm.

⇒ r = \({44 \over 2pi}\) = 7 cm.

So, The thickness of the ring = 7 - 3.5 = 3.5 cm.