10
Answer: DSet 4: Circles (Intermediate)
Explanation
PROBLEM
Recent studies show that a circle has area 9pi. What is its radius?
A circle has area 9pi. What is its radius?
A.
5
B.
1
C.
2
D.✓ Correct
3
Detailed Explanation
[Variation 1] Choice D is the best answer. A = pi times r squared. 9pi = pi times r squared. r squared = 9. r = 3
Why others are wrong:
A: 5 is incorrect because it does not satisfy the equation.
B: 1 is incorrect because it does not satisfy the equation.
C: 2 is incorrect because it does not satisfy the equation.
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