Question

The circumference of the earth is about 25,000 miles. Approximately how far is it from any point on the earth's surface to its center?

7,962 miles

3,981 miles

12,500 miles

78,500 miles

Answer 1

Circumference = 2*pi*r
r = radius
25000/2 = (2*pi*r)/2
12500/pi = (pi*r)/pi
3978.87 = r
the answer is 3981
* I know that the answers are not exactly the same, but with something like this it is best to go with the closet answer.

Answer 2

3981 miles

Explanation:

Circumference refers to the perimeter of circle . Let r be the radius of circle then it's circumference is given by
`2\pi r` where
`\pi =3.14` .

Here, circumference = 25,000 miles .

We need to find distance between the point on earth's surface and the centre i.e we need to find radius here .

Circumference =
`2\pi r`

`25000=2(3.14) r\\25000=6.28r`

On dividing both sides by 6.28 , we get

`(25000)/(6.28)=(6.28r)/(6.28)\\\\(25000)/(6.28)=r\\\\3980.89=r`

On rounding off the value of radius r , we get

`3981=r`

So, distance between point on earth's surface and centre is 3981 miles .