Two concentric circles have radii in the ratio 5 : 3. The area of the ring is 256π . Find the outer radius.
Options
A
27 cm
B
24 cm
C
20 cm
D
28 cm
Answer & Analysis
Answer
C
Analysis
Question Analysis
The main focus is using the ratio of radii and the area of the ring to find the outer radius. We'll represent the radii using a common variable, apply the ring - area formula, and solve for the variable to get the outer radius.
Key Concept Explanation
The area of a ring is , where is the outer radius and is the inner radius. When radii are in a ratio, we can express them as multiples of a variable to simplify calculations.
Step - by - Step Solution
1. Let the outer radius and the inner radius (x > 0).
2. Substitute into the ring - area formula: .
3. Given , set up the equation
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