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Which of the following pairs could be reasonable approximations for the diameter and circumference of a circle? 18 inches and 57 inches 3 centimeters and 28 centimeters 33 meters and 80 meters

User Look Left
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2 Answers

1 vote

Answer:

First option: 18 inches diameter, 57 inches circumference

Explanation:

Circumference of a circle is...

2 * radius * pi

We can approximate pi (3.14159...) to 3.

So the circumference of a circle is approx.

2 * radius * 3

We know the diameter of a circle is 2 times the radius...

diameter = 2 * radius

Thus, the circumference of a circle is approximately...

diameter * 3

First option:

Diameter 18, circumference 57

Let's try our approximation

18 * 3 = 54

We see that 57 is pretty close and is a reasonable approximation.

Second option:

Diameter 3, circumference 28

3 * 3 = 9

Not even close to 28.

Third option:

Diameter 33, circumference 80

3 * 33 = 99

Closer, but much further off than our first option.

User Hassan Sadeghi
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8.4k points
6 votes

Answer:

18 inches and 57 inches

Explanation:

The diameter and the circumference of a circle are proportionate to each other.

The circumference of a circle will always be the diameter times
\pi. We know this because the circumference of a circle is represented as


2 \pi r

Since the diameter is twice the radius, we multiply the radius by 2 - there's already a
\cdot 2 in this equation, so
c = \pi d.

1st option:
18\cdot3.14 = 56.52, this is close to 57 so it's reasonable.

2nd option:
3\cdot 3.14 = 9.42, this isn't close to 28 at all.

3rd option:
33 \cdot 3.14 = 103.62, this isn't close to 80 at all.

So the 1st option is reasonable.

Hope this helped!

User Lillemets
by
8.2k points

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