Finding the circumference and diameter of a circle

1. 1. Sally purchased a CD that was 5 inches in diameter. What is the circumference of the CD?

25 inches

15.7 inches

14 inches

20 inches

The circumference of a circle can be calculated using the formula C = πd, where C is the circumference and d is the diameter. In this case, the diameter of the CD is given as 5 inches. Plugging this value into the formula, we get C = π(5) = 15.7 inches. Therefore, the correct answer is 15.7 inches.

Explanation

The circumference of a circle can be calculated using the formula C = πd, where C is the circumference and d is the diameter. In this case, the diameter of the CD is given as 5 inches. Plugging this value into the formula, we get C = π(5) = 15.7 inches. Therefore, the correct answer is 15.7 inches.

2. If the diameter of a circle is 15 cm, what is the circumference of the circle?

45.1 cm

46.1 cm

47.1 cm

48.1 cm

The circumference of a circle is calculated by multiplying the diameter by pi (π). In this case, the diameter is given as 15 cm. Using the formula, the circumference can be calculated as 15 cm * π ≈ 47.1 cm. Therefore, the correct answer is 47.1 cm.

Explanation

The circumference of a circle is calculated by multiplying the diameter by pi (π). In this case, the diameter is given as 15 cm. Using the formula, the circumference can be calculated as 15 cm * π ≈ 47.1 cm. Therefore, the correct answer is 47.1 cm.

3. The basketball team plays with a ball with a radius of 6 inches. What is the circumference of each basketball?

36.68 inches

37.68 inches

38.68 inches

39.68 inches

The circumference of a circle can be calculated using the formula C = 2πr, where C is the circumference and r is the radius. In this case, the given radius is 6 inches. Plugging this value into the formula, we get C = 2π(6) = 12π ≈ 37.68 inches. Therefore, the correct answer is 37.68 inches.

Explanation

The circumference of a circle can be calculated using the formula C = 2πr, where C is the circumference and r is the radius. In this case, the given radius is 6 inches. Plugging this value into the formula, we get C = 2π(6) = 12π ≈ 37.68 inches. Therefore, the correct answer is 37.68 inches.

4. The laundry basket that Mrs. Smith uses for recycling has a diameter of 25 cm. She wants to move the basket to another place in her classroom. In order for her to complete this task, she must know the circumference of the basket. Please find the circumference of the basket so Mrs. Smith can determine where to place it.

76.5 cm

77.5 cm

78.5 cm

79.5 cm

To find the circumference of a circle, we use the formula C = πd, where C is the circumference and d is the diameter. Given that the diameter of the basket is 25 cm, we can substitute this value into the formula to find the circumference. C = π(25) = 78.5 cm. Therefore, the circumference of the basket is 78.5 cm.

Explanation

To find the circumference of a circle, we use the formula C = πd, where C is the circumference and d is the diameter. Given that the diameter of the basket is 25 cm, we can substitute this value into the formula to find the circumference. C = π(25) = 78.5 cm. Therefore, the circumference of the basket is 78.5 cm.

5. Nathan and three of his friends were building a duck blind to go hunting. They knew for all of them to fit inside that they needed a circumference of 15.7 yards. What diameter must the blind have for it to have the correct circumference?

3 yards

4 yards

5 yards

6 yards

The circumference of a circle is calculated using the formula C = πd, where C is the circumference and d is the diameter. In this case, the circumference needed is 15.7 yards. To find the diameter, we can rearrange the formula to solve for d: d = C/π. Plugging in the given circumference of 15.7 yards and the value of π (approximately 3.14), we find that the diameter must be 15.7/3.14 = 5 yards. Therefore, the correct answer is 5 yards.

Explanation

The circumference of a circle is calculated using the formula C = πd, where C is the circumference and d is the diameter. In this case, the circumference needed is 15.7 yards. To find the diameter, we can rearrange the formula to solve for d: d = C/π. Plugging in the given circumference of 15.7 yards and the value of π (approximately 3.14), we find that the diameter must be 15.7/3.14 = 5 yards. Therefore, the correct answer is 5 yards.

6. When determine the circumference of a circle, you must find the ____________ and multiply it by 3.14.

Area

Radius

Circumference

Diameter

To determine the circumference of a circle, you must find the diameter and multiply it by 3.14 (an approximation of pi, π). The formula for calculating the circumference of a circle is C = π * d, where "C" represents the circumference, "d" represents the diameter, and π is approximately equal to 3.14.

The diameter is the distance across the circle through the center, while the radius is the distance from the center of the circle to any point on its edge. To calculate the circumference using the radius, you can use the formula C = 2 * π * r, where "r" represents the radius.

Explanation

To determine the circumference of a circle, you must find the diameter and multiply it by 3.14 (an approximation of pi, π). The formula for calculating the circumference of a circle is C = π * d, where "C" represents the circumference, "d" represents the diameter, and π is approximately equal to 3.14.

The diameter is the distance across the circle through the center, while the radius is the distance from the center of the circle to any point on its edge. To calculate the circumference using the radius, you can use the formula C = 2 * π * r, where "r" represents the radius.

7. The table we have to sit at has a circumference of 6.28 yards. We need to find the diameter of the table.

1 yard

2 yards

3 yards

4 yards

The circumference of a circle is calculated by multiplying the diameter by pi (π). In this case, the circumference is given as 6.28 yards. To find the diameter, we need to divide the circumference by pi. Dividing 6.28 yards by pi gives us approximately 2 yards. Therefore, the diameter of the table is 2 yards.

Explanation

The circumference of a circle is calculated by multiplying the diameter by pi (π). In this case, the circumference is given as 6.28 yards. To find the diameter, we need to divide the circumference by pi. Dividing 6.28 yards by pi gives us approximately 2 yards. Therefore, the diameter of the table is 2 yards.

8. The radius of a circle tells

The distance around the outside of the circle.

The distance across the whole circle.

The distance from the midpoint around the outside.

The distance from the midpoint to one side of the circle.

The radius of a circle is the distance from the midpoint to one side of the circle. It is a line segment that connects the center of the circle to any point on its circumference. The radius is always the same length regardless of where it is measured from. It is different from the diameter, which is the distance across the whole circle.

Explanation

The radius of a circle is the distance from the midpoint to one side of the circle. It is a line segment that connects the center of the circle to any point on its circumference. The radius is always the same length regardless of where it is measured from. It is different from the diameter, which is the distance across the whole circle.

9. When measuring the hula hoop in class, group C discovered that it had a radius of 7 inches. What is the circumference of the hula hoop?

40 inches

37.6 inches

44 inches

49.6 inches

The circumference of a circle can be calculated using the formula:

Circumference = 2πr

Where:

C is the circumference

π (pi) is approximately 3.14159

r is the radius of the circle

In this case, the radius of the hula hoop is 7 inches. So, plug this value into the formula:

Circumference = 2 * π * 7 inches Circumference ≈ 2 * 3.14159 * 7 inches Circumference ≈ 6.28318 * 7 inches Circumference ≈ 44 inches (rounded to the nearest inch)

So, the circumference of the hula hoop is approximately 44 inches.

Explanation

The circumference of a circle can be calculated using the formula:

Circumference = 2πr

Where:

C is the circumference

π (pi) is approximately 3.14159

r is the radius of the circle

In this case, the radius of the hula hoop is 7 inches. So, plug this value into the formula:

Circumference = 2 * π * 7 inches Circumference ≈ 2 * 3.14159 * 7 inches Circumference ≈ 6.28318 * 7 inches Circumference ≈ 44 inches (rounded to the nearest inch)

So, the circumference of the hula hoop is approximately 44 inches.

Finding The Circumference And Diameter Of A Circle