Question 83

The inner and outer circumference of a circular ring is 22 cm and 44 cm, respectively. What is the thickness of the ring?

Solution

The inner and outer circumference of a circular ring is 22 cm and 44 cm, respectively.

Let r1 and r2 be the inner and outer radius of the ring.

$$2\pi \times r1 = 22$$

$$ r1 = \frac{7}{2}$$

$$2\pi \times r2 = 44$$

$$r2 = 7$$

Thickness $$= r2-r1 = 7 - \frac{7}{2} = \frac{7}{2} = 3.5$$

OPtion C is correct.

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