Verified Answer :

Circumference = \(\pi d\)

We know that the circumference in here is equal to 23000 miles. 

23000 = pi x d 

pi will be approximated to 3.14 

23000 = 3.14d 

divide both sides by 3.14 to get 
about 7325 as the diameter 

Circumference=\(\pi D\)
23000=3.142D
D=\(\frac{23000}{3.142}\)
D=7320.17
D=7320 miles