Circumference of a Circle Challenge

What is the formula to calculate the circumference of a circle?

• C = 2r²

• C = πd

• C = 4r

• C = 2πr

If the radius of a circle is 5 cm, what is its circumference?

• 15.70 cm

• 25.12 cm

• 40.84 cm

• 31.42 cm

A circle has a diameter of 10 m. What is its circumference?

• 25.12 m

• 15.70 m

• 31.42 m

• 40.00 m

If the circumference of a circle is 31.4 cm, what is its radius?

• 7 cm

• 3 cm

• 5 cm

• 10 cm

What is the circumference of a circle with a radius of 7 inches?

• Approximately 31.42 inches

• Approximately 50.24 inches

• Approximately 28.27 inches

• Approximately 43.98 inches

If a circle has a circumference of 62.8 cm, what is its diameter?

• 30 cm

• 20 cm

• 25 cm

• 15 cm

How does the circumference change if the radius is doubled?

• The circumference increases by 50%.

• The circumference doubles.

• The circumference remains the same.

• The circumference triples.

If the circumference of a circle is 12.56 m, what is the diameter?

• 5 m

• 3 m

• 6 m

• 4 m

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

• 15.7 feet

• 28.0 feet

• 10.5 feet

• 21.99 feet

If the diameter of a circle is 8 cm, what is its circumference?

• 15.7 cm

• 30.16 cm

• 20 cm

• 25.13 cm