Question

which is the best estimate of the circumference of this circle?

a. 3 units
b. 9 units
c. 1.5 units
d. 30 units

Explanation:

Identify the given radius

$$ r = 1.5 $$

Calculate the exact circumference

$$ C = 2 \pi r = 2 \cdot \pi \cdot 1.5 = 3\pi \approx 3 \cdot 3.14159 = 9.42 $$

Determine the best estimate among the choices

$$ 9.42 \approx 9 $$

Answer:

• A. 3 units
• B. 9 units (Correct answer)
• C. 1.5 units
• D. 30 units