1. **State the problem:** We have a rectangular board of dimensions 30 ft by 20 ft, with two circles inside it. The small circle has a diameter of 6 ft, and the large circle has a diameter of 10 ft. We want to find the probabilities of landing in each circle when an arrow is randomly thrown at the board.
2. **Formula for probability:** Probability of landing in a region = \( \frac{\text{Area of the region}}{\text{Area of the board}} \).
3. **Calculate the area of the board:**
$$\text{Area}_{board} = 30 \times 20 = 600 \text{ ft}^2$$
4. **Calculate the area of the small circle:**
Diameter = 6 ft, so radius \(r_s = \frac{6}{2} = 3\) ft.
$$\text{Area}_{small} = \pi r_s^2 = \pi \times 3^2 = 9\pi \approx 28.27 \text{ ft}^2$$
5. **Calculate the area of the large circle:**
Diameter = 10 ft, so radius \(r_l = \frac{10}{2} = 5\) ft.
$$\text{Area}_{large} = \pi r_l^2 = \pi \times 5^2 = 25\pi \approx 78.54 \text{ ft}^2$$
6. **Calculate the probability of landing in the small circle:**
$$P_{small} = \frac{\text{Area}_{small}}{\text{Area}_{board}} = \frac{9\pi}{600} = \frac{\cancel{3} \times 3 \pi}{\cancel{3} \times 200} = \frac{3\pi}{200} \approx \frac{3 \times 3.1416}{200} = \frac{9.4248}{200} = 0.0471$$
7. **Calculate the probability of landing in the large circle:**
$$P_{large} = \frac{\text{Area}_{large}}{\text{Area}_{board}} = \frac{25\pi}{600} = \frac{\cancel{25} \pi}{\cancel{25} \times 24} = \frac{\pi}{24} \approx \frac{3.1416}{24} = 0.1309$$
8. **Calculate the probability of landing in either circle:**
$$P_{either} = P_{small} + P_{large} = 0.0471 + 0.1309 = 0.178 \approx 0.18$$
9. **Compare with the options:**
- A. Probability of landing in a circle is approximately 0.18. **True**
- B. Probability of landing in the small circle is approximately 0.03. **False** (calculated 0.0471)
- C. Probability of landing in the large circle is approximately 0.05. **False** (calculated 0.1309)
- D. Probability of landing in the large circle is approximately 0.13. **True**
- E. Probability of landing in the small circle is approximately 0.19. **False**
**Final answers:** A and D are true.
Circle Probabilities C40616
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