The equation for the circumference of a circle is C = πd where d is the diameter.
If we rearrange this to make d the subject we get d = C/π which is 23.864/π because our circumference is 23.864 feet.
If you calculate this you will get roughly 7.6 feet.
Some people prefer the answer to be in metres so if that’s the case then 7.6 feet ≈ 2.31 metres.
Hope this helps