Perimeter, area and volume · Ages 11–12
Circumference worksheet
Part of: Circumference and area of a circle
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Circumference worksheet
Perimeter, area and volume · Ages 11–12
Numsprite
numsprite.com
Name:Date:Score:／48
Write each answer in the space. For word problems, show your working and write a sentence answer.
Part A: Working out and filling in (2 marks each)
1.Find the circumference of this circle. (Take π as 3.14.) The answer is cm
Answer:
2.Take π as 227. What is the circumference of a circle 42 cm across, in cm?
Answer:
3.Find the circumference of this circle. (Take π as 3.14.) The answer is cm
Answer:
4.Take π as 227. What is the circumference of a circle 49 cm across, in cm?
Answer:
5.Take π as 227. What is the circumference of a circle 28 cm across, in cm?
Answer:
Part B: Choose, or true or false (2 marks each)
6.A circle is 7 cm across. Without working it out, about how long is its circumference?
- A. 42 cm
- B. 7 cm
- C. 14 cm
- D. A little more than 21 cm
Choose the right answer
Answer:
7.A circle is 4 cm across. Without working it out, about how long is its circumference?
- A. A little more than 12 cm
- B. 4 cm
- C. 24 cm
- D. 8 cm
Choose the right answer
Answer:
8.A circle of radius 3 cm has a circumference of 18.84 cm. (Take π as 3.14.)
True or false?
Answer:
9.A circle 26 cm across has a radius of 13 cm and a circumference of 81.64 cm. Which division gives π?
- A. 26 ÷ 13
- B. 81.64 ÷ 26
- C. 13 ÷ 26
- D. 81.64 ÷ 13
Choose the right answer
Answer:
10.A circle 22 cm across has a radius of 11 cm and a circumference of 69.08 cm. Which division gives π?
- A. 11 ÷ 22
- B. 69.08 ÷ 11
- C. 69.08 ÷ 22
- D. 22 ÷ 11
Choose the right answer
Answer:
11.A circle of radius 20 cm has a circumference of 62.8 cm. (Take π as 3.14.)
True or false?
Answer:
12.Which circle has the longest circumference?
- A. A circle 17 cm across
- B. A circle of radius 7 cm
- C. A circle 15 cm across
- D. A circle of radius 8 cm
Choose the right answer
Answer:
Part C: Word problems (4 marks each)
13.Take π as 3.14. Ka-lok's round table is 70 cm across. Lace goes once round its edge. At least how many centimetres of lace are needed?
Working:
Answer:
14.Take π as 3.14. A round pond is 16 m across. Ka-yee runs 3 times round its edge. How many metres is that?
Working:
Answer:
15.Take π as 3.14. A big clock's minute hand is 16 cm long. How many centimetres does its tip travel in 3 hours?
Working:
Answer:
16.Take π as 227. The big wheel on the harbourfront has a radius of 49 m. How many metres does a cabin travel in one turn?
Working:
Answer:
17.Take π as 227. The big wheel on the harbourfront has a radius of 35 m. How many metres does a cabin travel in one turn?
Working:
Answer:
18.Take π as 3.14. A big clock's minute hand is 18 cm long. How many centimetres does its tip travel in 3 hours?
Working:
Answer:
Show the answers and working
Circumference worksheet: Answers and working
Part A: Working out and filling in
1. 81.64
The 26 cm in the picture is the diameter. Circumference = 3.14 × diameter.
Circumference = 3.14 × diameter = 3.14 × 26 = 81.64.
2. 132 cm
Circumference = 227 × 42. 42 is a multiple of 7, so do 42 ÷ 7 first.
227 × 42 = 22 × 6 = 132: with a diameter in sevens, 227 is handy.
3. 56.52
The picture gives the radius, 9 cm. Find the diameter first: twice the radius.
The picture gives the radius: diameter = 9 × 2 = 18; 3.14 × 18 = 56.52.
4. 154 cm
Circumference = 227 × 49. 49 is a multiple of 7, so do 49 ÷ 7 first.
227 × 49 = 22 × 7 = 154: with a diameter in sevens, 227 is handy.
5. 88 cm
Circumference = 227 × 28. 28 is a multiple of 7, so do 28 ÷ 7 first.
227 × 28 = 22 × 4 = 88: with a diameter in sevens, 227 is handy.
Part B: Choose, or true or false
6. D. A little more than 21 cm
The circumference is π times the diameter, and π is a little more than 3. Work out 7 × 3 first.
Every circle's circumference is π times its diameter, π about 3.14: 7 × 3 = 21, so a little more than 21 cm.
7. A. A little more than 12 cm
The circumference is π times the diameter, and π is a little more than 3. Work out 4 × 3 first.
Every circle's circumference is π times its diameter, π about 3.14: 4 × 3 = 12, so a little more than 12 cm.
8. True
3 cm is the radius. Find the diameter, multiply by 3.14, and compare with 18.84.
Circumference = 3.14 × diameter, and the diameter is twice the radius: 3.14 × 3 × 2 = 18.84.
9. B. 81.64 ÷ 26
π links the circumference to the diameter: the circumference is π times the diameter. Which division is circumference ÷ diameter?
π is circumference ÷ diameter: 81.64 ÷ 26 = 3.14, for every circle.
10. C. 69.08 ÷ 22
π links the circumference to the diameter: the circumference is π times the diameter. Which division is circumference ÷ diameter?
π is circumference ÷ diameter: 69.08 ÷ 22 = 3.14, for every circle.
11. False
20 cm is the radius. Find the diameter, multiply by 3.14, and compare with 62.8.
Circumference = 3.14 × diameter, and the diameter is twice the radius: 3.14 × 20 × 2 = 125.6.
12. A. A circle 17 cm across
Some give the diameter and some the radius. Turn each into a diameter first, then compare.
Turn each into a diameter and compare: 17, 16, 15 and 14 cm; the longer the diameter, the longer the circumference, so the circle 17 cm across wins.
Part C: Word problems
Marking: 2 for the working, 1 for the answer, 1 for the sentence.
13. 219.8 cm
Once round is the circumference. The table is 70 cm across, and circumference = 3.14 × diameter.
Once round is the circumference: 3.14 × 70 = 219.8.
14. 150.72 m
Find one lap first, circumference = 3.14 × 16, then think about 3 laps.
One lap is 3.14 × 16 = 50.24 m; 3 laps are 50.24 × 3 = 150.72 m.
15. 301.44 cm
The minute hand goes round once an hour, its tip on a circle of radius 16 cm. Work out one turn first.
The minute hand goes round once an hour, its tip along a circle of radius 16: 3.14 × 16 × 2 = 100.48; 3 hours: 100.48 × 3 = 301.44.
16. 308 m
One turn is the circumference. 49 is the radius, so find the diameter, then multiply by 227.
Diameter = 49 × 2 = 98; 227 × 98 = 308.
17. 220 m
One turn is the circumference. 35 is the radius, so find the diameter, then multiply by 227.
Diameter = 35 × 2 = 70; 227 × 70 = 220.
18. 339.12 cm
The minute hand goes round once an hour, its tip on a circle of radius 18 cm. Work out one turn first.
The minute hand goes round once an hour, its tip along a circle of radius 18: 3.14 × 18 × 2 = 113.04; 3 hours: 113.04 × 3 = 339.12.
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