Find Circumference of each circle in terms of pie?

Question

4) 16
5)16(radius)
6)3.9

Answer 1

1.pi(16)=16pi (i have taken dia as 16)
2.2pi(16)=32pi
3.pi(3.9)=3.9pi
where you haven't specified i have taken it as the diameter
if the dia is given C=pi(d)
if the radius is given C=2pi(r)

Answer 2

C = Pi*D or the circumference is the same as Pi times the diameter.

So, if D is 16, then C = 16*Pi

If the radius is 16, then the diameter is 32, so C = 32*Pi

I don't know what it is that is supposed to be 3.9.
If it is the diameter, then C = 3.9*Pi

Answer 3

The circumference of a pie? Is it apple or blueberry?

Answer 4

I <3 punch and pie!

Answer 5

4) 3.1415 x 16 = 50.264

5) 3.1415 x (2)(16) =100.528

6) 3.1415 x 3.9 = 12.2519