Let’s solve each problem step by step.
We are told to use the formula:
Circumference = 2 × π × r
and assume
π = 3.14
Remember:
- If you’re given the
diameter, divide it by 2 to get the radius (r).
- If you’re given the
radius, plug it directly into the formula.
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Problem 1: Diameter = 42 yd → Radius = 42 ÷ 2 = 21 yd
Circumference = 2 × 3.14 × 21 = 6.28 × 21
→ 6.28 × 20 = 125.6, plus 6.28 × 1 = 6.28 → Total =
131.88 yd
Problem 2: Diameter = 22 ft → Radius = 22 ÷ 2 = 11 ft
Circumference = 2 × 3.14 × 11 = 6.28 × 11
→ 6.28 × 10 = 62.8, plus 6.28 × 1 = 6.28 → Total =
69.08 ft
Problem 3: Radius = 17 in (already given)
Circumference = 2 × 3.14 × 17 = 6.28 × 17
→ 6.28 × 10 = 62.8, 6.28 × 7 = 43.96 → Total = 62.8 + 43.96 =
106.76 in
Problem 4: Radius = 91 yd
Circumference = 2 × 3.14 × 91 = 6.28 × 91
Break it down:
6.28 × 90 = 565.2
6.28 × 1 = 6.28
Total = 565.2 + 6.28 =
571.48 yd
Problem 5: Radius = 40 m
Circumference = 2 × 3.14 × 40 = 6.28 × 40
→ 6 × 40 = 240, 0.28 × 40 = 11.2 → Total =
251.2 m
Problem 6: Radius = 44 cm
Circumference = 2 × 3.14 × 44 = 6.28 × 44
Break it down:
6.28 × 40 = 251.2
6.28 × 4 = 25.12
Total = 251.2 + 25.12 =
276.32 cm
Problem 7: Radius = 32 yd
Circumference = 2 × 3.14 × 32 = 6.28 × 32
Break it down:
6.28 × 30 = 188.4
6.28 × 2 = 12.56
Total = 188.4 + 12.56 =
200.96 yd
Problem 8: Diameter = 12.5 ft → Radius = 12.5 ÷ 2 = 6.25 ft
Circumference = 2 × 3.14 × 6.25 = 6.28 × 6.25
Let’s compute:
6.28 × 6 = 37.68
6.28 × 0.25 = 1.57
Total = 37.68 + 1.57 =
39.25 ft
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Final Answer:
1. 131.88 yd
2. 69.08 ft
3. 106.76 in
4. 571.48 yd
5. 251.2 m
6. 276.32 cm
7. 200.96 yd
8. 39.25 ft
Parent Tip: Review the logic above to help your child master the concept of circumference worksheet pdf.
