Circle Circumference and Area Quiz

What is the formula for the circumference of a circle if the diameter is given?

Answer explanation

The correct formula for the circumference of a circle when the diameter is given is C = πd.

Tags

CCSS.7.G.B.4

What is the formula for the area of a circle?

Answer explanation

The correct formula for the area of a circle is A = πr^2, where r is the radius of the circle. This formula is derived from the definition of the area of a circle as π times the square of the radius.

Tags

CCSS.7.G.B.4

If the radius of a circle is 7 cm, what is its circumference?

• 14 cm

• 22 cm

• 44 cm

• 88 cm

Answer explanation

The circumference of a circle is calculated using the formula 2 * π * radius. Substituting the radius (7 cm) into the formula gives 2 * 3.14 * 7 = 44 cm. Therefore, the correct answer is 44 cm.

Tags

CCSS.7.G.B.4

If the diameter of a circle is 10 inches, what is its area?

Answer explanation

The area of a circle is calculated using the formula A = πr^2. Since the diameter is given, we need to divide it by 2 to get the radius. So, radius = 10 / 2 = 5 inches. Therefore, the area is A = π(5)^2 = 78.5 in^2.

Tags

CCSS.7.G.B.4

A circle has a circumference of 62.8 meters. What is the diameter of the circle?

• 10 m

• 20 m

• 30 m

• 40 m

Answer explanation

The circumference of a circle is calculated using the formula C = πd. Given C = 62.8 m, we can solve for the diameter (d) by rearranging the formula to d = C / π = 62.8 / 3.14 = 20 m. Therefore, the diameter of the circle is 20 meters.

Tags

CCSS.7.G.B.4

A circular garden has an area of 314 square feet. What is the radius of the garden?

• 5 ft

• 10 ft

• 15 ft

• 20 ft

Answer explanation

The area of a circle is calculated using the formula A = πr^2. Given A = 314 sq ft, solving for r gives r = √(314/π) ≈ 10 ft. Therefore, the radius of the garden is 10 ft.

Tags

CCSS.7.G.B.4

If the radius of a circle is doubled, by what factor does the circumference increase?

• 2

• 3

• 4

• 8

Answer explanation

When the radius is doubled, the circumference increases by a factor of 2. This is because the circumference is directly proportional to the radius in a circle.

Tags

CCSS.7.G.B.4

If the diameter of a circle is halved, by what factor does the area decrease?

• 2

• 3

• 4

• 8

Answer explanation

When the diameter of a circle is halved, the radius is also halved. Since the area of a circle is proportional to the square of the radius, the area decreases by a factor of 4 (2^2).

Tags

CCSS.7.G.B.4

What is the circumference of a circle with a radius of 3.5 cm?

• 7 cm

• 14 cm

• 21 cm

• 22 cm

Answer explanation

The circumference of a circle is calculated using the formula 2 * π * radius. Substituting the radius of 3.5 cm gives 2 * 3.14 * 3.5 = 22 cm, which is the correct answer.

Tags

CCSS.7.G.B.4

A circular track has a diameter of 400 meters. What is the approximate length of the track?

• 1256 m

• 628 m

• 314 m

• 200 m

Answer explanation

The circumference of a circle is calculated using the formula C = π * d, where d is the diameter. So, C = π * 400 = 1256 m. However, the question asks for the length of the track, which is half the circumference, so it is approximately 628 m.

Tags

CCSS.7.G.B.4