A dartboard consists of a circle inscribed in a square. The area of the circle is 25π square units. The area of the square is 100 square units.

A dartboard consists of a circle inscribed in a square.

Megan randomly throws a dart at the square. Assuming the dart lands within the square, what is the probability that the dart lands within the dartboard? Round your answer to the nearest tenth of a percent.

1 answer

To find the probability that a dart thrown at a square lands within the inscribed circle (the dartboard), we can use the areas of the circle and the square.

  1. Area of the Circle: The area of the circle is given as: \[ A_{\text{circle}} = 25\pi \text{ square units} \]

  2. Area of the Square: The area of the square is given as: \[ A_{\text{square}} = 100 \text{ square units} \]

  3. Probability Calculation: The probability \( P \) that the dart lands within the circle is the ratio of the area of the circle to the area of the square: \[ P = \frac{A_{\text{circle}}}{A_{\text{square}}} \]

    Substituting the areas: \[ P = \frac{25\pi}{100} \]

    Simplifying this expression: \[ P = \frac{25\pi}{100} = \frac{\pi}{4} \]

  4. Numerical Value: To find the probability in numerical form, we approximate \( \pi \): \[ P \approx \frac{3.14}{4} \approx 0.785 \]

  5. Percentage Conversion: Convert this probability into a percentage: \[ P \times 100 \approx 0.785 \times 100 \approx 78.5% \]

  6. Rounding: Rounding to the nearest tenth of a percent gives us: \[ \text{Probability} \approx 78.5% \]

Thus, the final answer is: \[ \boxed{78.5%} \]