Practice identifying radius and diameter, using their relationship, and finding circumference with pi.
Read each problem carefully. Use 3.14 for pi unless the problem says otherwise. Show your work in the space provided.
Find and use circle measurements with pi
Math - Grade 6-8
- 1
A circle has a radius of 6 cm. What is its diameter?
- 2
A circle has a diameter of 18 inches. What is its radius?
- 3
A circle has a diameter of 10 meters. Find its circumference using 3.14 for pi.
- 4
A circle has a radius of 4 feet. Find its circumference using 3.14 for pi.
- 5
A bicycle wheel has a diameter of 26 inches. How far does the bike move in one full turn of the wheel? Use 3.14 for pi.
- 6
The circumference of a circular table is 94.2 inches. What is the diameter of the table? Use 3.14 for pi.
- 7
The diameter of a round clock face is 12 inches. What is the circumference of the clock face? Use 3.14 for pi.
- 8
A circle has a circumference of 62.8 centimeters. What is its radius? Use 3.14 for pi.
- 9
Circle A has a radius of 5 cm. Circle B has a diameter of 8 cm. Which circle has the greater circumference? Use 3.14 for pi.
- 10
A circular garden has a radius of 7 meters. A gardener wants to place edging around the outside. How many meters of edging are needed? Use 3.14 for pi.
- 11
A student says, "The radius of a circle is always longer than the diameter." Explain whether the student is correct.
- 12
A circle has a diameter of 15 units. Write the circumference in terms of pi, then estimate it using 3.14 for pi.
- 13
A jar lid has a circumference of 25.12 cm. What is the diameter of the lid? Use 3.14 for pi.
- 14
A circular running track has a diameter of 100 meters. A runner completes 3 laps. How far does the runner travel? Use 3.14 for pi.
- 15
Two circles have the same center. The smaller circle has a radius of 3 cm, and the larger circle has a radius of 9 cm. How many times greater is the larger circle's circumference than the smaller circle's circumference?