Question

13 multiple choice 1 point
if the diameter of a circle is 4, the radius must be
2
1/2
4
8

14 multiple choice 1 point
if the radius of a circle is 3 meters, what is its circumference? round your solution to the nearest tenth.
28.2 m
12.4 m
9.4 m
18.8 m

15 multiple choice 1 point
find the area of a circle with a radius of 18 in. use 3.14 for pi and round your solution to the nearest tenth.
56.5 \text{ in}^2
1,017.4 \text{ in}^2
177.5 \text{ in}^2
113 \text{ in}^2

Explanation:

Calculate the radius from the diameter

$$ r = \frac{d}{2} = \frac{4}{2} = 2 $$

Calculate the circumference of the circle

$$ C = 2\pi r = 2 \cdot \pi \cdot 3 = 6\pi \approx 18.8495\text{ m} \approx 18.8\text{ m} $$

Calculate the area of the circle

$$ A = \pi r^2 \approx 3.14 \cdot 18^2 = 3.14 \cdot 324 = 1017.36\text{ in}^2 \approx 1017.4\text{ in}^2 $$

Answer:

Question 13

• (A) 2 (Correct answer)
• (B) 1/2
• (C) 4
• (D) 8

Question 14

• (A) 28.2 m
• (B) 12.4 m
• (C) 9.4 m
• (D) 18.8 m (Correct answer)

Question 15

• (A) 56.5 \(\text{in}^2\)
• (B) 1,017.4 \(\text{in}^2\) (Correct answer)
• (C) 177.5 \(\text{in}^2\)
• (D) 113 \(\text{in}^2\)