Set 5: Circles (Beginner)

[Variation 1] **Choice A is the best answer.** Circumference = 2 times pi times r = 2 times pi times 10 = 20pi

Explanation

Answer: A

PROBLEM

Recent studies show that a circle has radius 10. What is its circumference? (Express answer as a number times pi)

A circle has radius 10. What is its circumference? (Express answer as a number times pi)

20pi

✓ Correct

10pi

100pi

22pi

Detailed Explanation

[Variation 1] Choice A is the best answer. Circumference = 2 times pi times r = 2 times pi times 10 = 20pi

Why others are wrong:

B: 10pi is incorrect because it does not satisfy the equation.

C: 100pi is incorrect because it does not satisfy the equation.

D: 22pi is incorrect because it does not satisfy the equation.