Multiple choice

(\text{The area of the ring is } 418 \text{ cm}^2\text{ . If the radius of the smaller circle is 6 cm. The radius of the bigger circle is-})

  1. 18 cm.

  2. 16 cm.

  3. 13 cm.

  4. 10 cm.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Area of ring = π(R² - r²) where R is radius of larger circle, r is radius of smaller circle. Given π(R² - 6²) = 418, so R² - 36 = 418/π ≈ 133. Therefore R² ≈ 169 and R = 13 cm. Option A (18 cm) is incorrect. Option B (16 cm) would give area ≈ 678, not 418. Option D (10 cm) is too small.

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