Two concentric circles form a ring. The inner and outer circumferences of the ring are 22 cm and 44 cm, respectively. The width of the ring is:(Take $\pi =\frac{22}{7}$)
Answer & explanation
Correct answer: option 1
As the circumference of the inner circle = 22 cm
And of the outer circle = 44 cm
We know that,
Circumference of a circle = 2πR
Where R = Radius of the given circle, where π = \(\frac{22}{7}\)
So,
Let Us assume that the radius of the bigger circle be R unit
And the radius of the smaller circle be r unit
By using the above formula
= Circumference of the inner circle is 2× π × r = 22
= Circumference of the outer circle is 2× π × R = 44
= 2× \(\frac{22}{7}\) × r = 22
= 2× \(\frac{22}{7}\) × R = 44
= r = 3.5 cm
R = 7cm
So, The width of the ring is R – r = 7 – 3.5 = 3.5 cm