Answer :

The circumference of the circle formula is

[tex]C=2\pi r[/tex][tex]r\rightarrow radius[/tex][tex]\begin{gathered} diameter=7.8yd \\ r=\frac{diameter}{2}=\frac{7.8}{2}=3.9yd \\ \end{gathered}[/tex][tex]\begin{gathered} C=2\pi r \\ C=2\times\pi\times3.9 \\ C=24.5yd \end{gathered}[/tex]

Hence, the circumference of the circle is 24,5yd