1.
The radius of a circle is 3 inches. What is the area?
Correct Answer
C. 28.26 inches squared
Explanation
3 x 3 x 3.14
2.
The diameter of a circle is 8 centimeters. What is the area?
Correct Answer
A. 50.24 centimeters squared
Explanation
Make sure you change the diameter to a radius. (divide by 2)
3.
A circle has a radius of 12 inches. What is the area of the circle?
Correct Answer
B. 452.16 inches squared
Explanation
To find the area of a circle, use the formula:
Area = π * r^2
where "r" is the radius of the circle.
Given:
Radius, r = 12 inches
Using the formula: Area = π * (12 inches)^2 Area = π * 144 square inches Area ≈ 3.14159 * 144 square inches Area ≈ 452.39 square inches
When rounded to two decimal places, the area is approximately 452.16 square inches.
4.
Mark has a circular swimming pool with are radius of 7 feet. If he wants a cover to go over the pool what is the least amount of material needed to cover the pool?
Correct Answer
C. 153.86 feet squared
Explanation
7 x 7 x 3.14
5.
Sam has baked a circular cake. The cake has a diameter of 10 inches. Sam needs to know how much icing it will take to cover the top of the cake; which of the following does Sam need to use to figure this out?
Correct Answer
C. 5 x 5 x 3.14
Explanation
Area = radius x radius x pi
6.
Molly is making pizza for supper and wants to cover the top of the pizza with sauce. She has measured the radius of the pizza to be 5 inches, how many square inches will the sauce cover?
Correct Answer
B. 78.5 inches squared
Explanation
The correct answer is 78.5 inches squared. To find the area of the top of the pizza that the sauce will cover, we need to calculate the area of a circle with a radius of 5 inches. The formula for the area of a circle is A = πr^2, where A is the area and r is the radius. Plugging in the given radius of 5 inches into the formula, we get A = π(5^2) = π(25) = 78.5 inches squared.
7.
Pam's mom is fixing cookies for her class. She wants to put icing on the cookies. The radius of the cookies is 2 inches. She is making 20 cookies, what is the area that the icing will cover if she icings all 20 cookies?
Correct Answer
A. 251.2 inches squared
Explanation
The area of a circle can be found using the formula A = πr^2, where A is the area and r is the radius. In this case, the radius of each cookie is given as 2 inches. So, the area of one cookie is A = π(2)^2 = 4π square inches. Since she is making 20 cookies, the total area that the icing will cover is 20 times the area of one cookie, which is 20 * 4π = 80π square inches. Approximating π as 3.14, the total area is approximately 251.2 square inches.
8.
A circular stool needs to be covered with new fabric. If the diameter of the stool is 2 feet, how much material is needed to cover the stool?
Correct Answer
C. 3.14 feet squared
Explanation
The correct answer is 3.14 feet squared. To find the amount of fabric needed to cover the circular stool, we need to calculate the area of the circle. The formula for the area of a circle is A = πr^2, where A is the area and r is the radius. In this case, the diameter of the stool is given as 2 feet, so the radius is 1 foot. Plugging this value into the formula, we get A = 3.14 * 1^2 = 3.14 feet squared.
9.
The radius is always half of the diameter.
Correct Answer
A. True
Explanation
The statement is true because the radius of a circle is defined as the distance from the center of the circle to any point on its circumference. The diameter, on the other hand, is the distance across the circle passing through the center. Since the diameter spans the entire circle, it is always twice the length of the radius. Therefore, the radius is always half of the diameter.
10.
The chord is the longest diameter in a circle.
Correct Answer
B. False
Explanation
The statement is false. A chord is a line segment that connects two points on a circle, but it does not have to pass through the center of the circle. The longest diameter in a circle is actually the line segment that passes through the center and has endpoints on the circle, also known as the diameter. Therefore, the chord is not the longest diameter in a circle.