4
Answer: CSet 5: Circles (Intermediate)
Explanation
PROBLEM
Intriguingly, a circle has area 49pi. What is its radius?
A circle has area 49pi. What is its radius?
A.
8
B.
9
C.✓ Correct
7
D.
6
Detailed Explanation
[Variation 2] Choice C is the best answer. A = pi times r squared. 49pi = pi times r squared. r squared = 49. r = 7
Why others are wrong:
A: 8 is incorrect because it does not satisfy the equation.
B: 9 is incorrect because it does not satisfy the equation.
D: 6 is incorrect because it does not satisfy the equation.