Circles (circumference, area) Knowledge-Based Practice

Questions

1. 1.

   The circumference of circle $A$ is three times the circumference of circle $B$. If the area of circle $B$ is $16\pi\text{ cm}^2$, what is the area of circle $A$?

   • A) $48\pi\text{ cm}^2$
   • B) $96\pi\text{ cm}^2$
   • C) $144\pi\text{ cm}^2$
   • D) $256\pi\text{ cm}^2$
2. 2.

   The sum of the circumferences of two circles is $28\pi\text{ cm}$, and the difference between their radii is $4\text{ cm}$. What is the area of the larger circle?

   • A) $81\pi\text{ cm}^2$
   • B) $49\pi\text{ cm}^2$
   • C) $25\pi\text{ cm}^2$
   • D) $18\pi\text{ cm}^2$
3. 3.

   Two concentric circles have circumferences of $12\pi\text{ cm}$ and $20\pi\text{ cm}$. What is the area of the region bounded between the two circles?

   • A) $16\pi\text{ cm}^2$
   • B) $64\pi\text{ cm}^2$
   • C) $32\pi\text{ cm}^2$
   • D) $128\pi\text{ cm}^2$
4. 4.

   A circle has a circumference of $12\pi\text{ cm}$. If its radius is increased by $4\text{ cm}$, what is the area of the new circle?

   • A) $100\pi\text{ cm}^2$
   • B) $256\pi\text{ cm}^2$
   • C) $52\pi\text{ cm}^2$
   • D) $20\pi\text{ cm}^2$
5. 5.

   A circle has an area of $64\pi\text{ cm}^2$. What is the circumference of this circle?

   • A) $8\pi\text{ cm}$
   • B) $16\pi\text{ cm}$
   • C) $32\pi\text{ cm}$
   • D) $64\pi\text{ cm}$

Answers and step-by-step solutions appear after you finish the test.