Let's solve each of the word problems step by step.
---
1. The radius of a circular cake is 5.5 cm long. How long is the diameter?
Concept:
The diameter (d) of a circle is twice the radius (r):
$$
d = 2r
$$
Given: $ r = 5.5 \, \text{cm} $
$$
d = 2 \times 5.5 = 11 \, \text{cm}
$$
✔ Answer: $ \boxed{11} $ cm
---
2. The radius of a circle is 15.6 cm long. How long is the diameter?
Again, use:
$$
d = 2r = 2 \times 15.6 = 31.2 \, \text{cm}
$$
✔ Answer: $ \boxed{31.2} $ cm
---
3. If the diameter of a circular field is 40m, what is the length of the radius?
Use:
$$
r = \frac{d}{2} = \frac{40}{2} = 20 \, \text{m}
$$
✔ Answer: $ \boxed{20} $ m
---
4. The center point of a circle is 11cm from its edge. What is the radius of the circle?
The distance from the center to the edge is the
radius by definition.
So, if the center is 11 cm from the edge, then:
✔ Answer: $ \boxed{11} $ cm
---
5. If a circular playground has a radius of 50 feet, what is the circumference? Solve using $ 2\pi r $.
Use the formula:
$$
C = 2\pi r
$$
Given: $ r = 50 $ feet
$$
C = 2 \times \pi \times 50 = 100\pi \, \text{feet}
$$
If you want a numerical value (using $ \pi \approx 3.14 $):
$$
C \approx 100 \times 3.14 = 314 \, \text{feet}
$$
But since the question says "solve using $ 2\pi r $", it’s acceptable to leave it in terms of $ \pi $.
✔ Answer: $ \boxed{100\pi} $ feet (or approximately $ \boxed{314} $ feet)
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✔ Final Answers:
1.
11 cm
2.
31.2 cm
3.
20 m
4.
11 cm
5.
$ 100\pi $ feet (or
314 feet)
Each question is worth 2 marks, so total: 10 marks.
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Parent Tip: Review the logic above to help your child master the concept of circumference word problems worksheet.
