30 inches
yes as long as the 15 year old is appropiate and has a sensible head
It should be anywhere from 6 and half inches to 13 inches with a circumference of 8 inches.
A 6 year old is in 1st grade.
The circumference is: 6*pi/pi = 6 units
Circumference of circle: 6*pi inches
Circumference of circle: 6*pi inches
The circumference of a circle with radius of 6 is about 37.7
That should be ok, but a 6 year old should not be in there for an extended period.
Since circumference equals pi times the diameter, if the diameter of a circle is 6, then its circumference is going to be pi times 6 or 6 pi.
Only if the 6 year old is black.
Circumference = 2*pi*6 inches