Question

2 ft

The circumference of the inner circle is 22 ft. The distance between the inner circle
and the outer circle is 2 ft. By how many feet is the circumference of outer circle
22
greater than the circumference of the inner circle? Use for .
7
C

Answer 1

88/7 ft = 12.6 ft (nearest tenth)

Explanation:

Circumference of a circle = 2
`\pi`r

Radius of inner circle

Given:

• circumference of inner circle = 22ft
• 
  `\pi` = 22/7

⇒ 22 = 2 x (22/7) x r

⇒ r = 3.5

So the radius of the inner circle is 3.5 ft

Radius of outer circle

If the distance between the inner circle and the outer circle is 2 ft, then the radius of the outer circle = 3.5 + 2 = 5.5

Circumference of outer circle

Therefore, circumference of outer circle:

= 2 x (22/7) x 5.5

= 242/7 ft

Difference between circumferences

Difference = outer circle circumference - inner circle circumference

= 242/7 - 22

= 88/7 ft

= 12.6 ft (nearest tenth)