2
Answer: BSet 4: Circles (Intermediate)
Explanation
PROBLEM
Recent studies show that a circle has area 25pi. What is its radius?
A circle has area 25pi. What is its radius?
A.
6
B.✓ Correct
5
C.
4
D.
3
Detailed Explanation
[Variation 1] Choice B is the best answer. A = pi times r squared. 25pi = pi times r squared. r squared = 25. r = 5
Why others are wrong:
A: 6 is incorrect because it does not satisfy the equation.
C: 4 is incorrect because it does not satisfy the equation.
D: 3 is incorrect because it does not satisfy the equation.