The complete formula for circumference is:
[tex] C=\pi d [/tex]
Since we know the circumference of the circle is 314 inches, we can then solve for d, the diameter:
[tex] 314=\pi d [/tex]
Using 3.14 for pi, we get:
[tex] 314=(3.14)d [/tex]
Then solve for d:
[tex] d=100 [/tex]
And now we know the diameter of the circle is 100 inches.