Question

What is the diameter of a circle if the circumference is 30

Answer 1

2×pie×r = 30
r = 4.7746
d = r×2
d = 9.55

Answer 2

the Circumference formula for a circle is C=2(pi)r
30= Circum.
Pi=3.14
and the radius times two is the diameter.

So it should look like this

30=d(3.14)

Divide pi by both sides

and the Diameter equals around 9.55