arc

$\frac{40}{360}\times \pi \times (8\times 2)$

$\frac{1}{9}\times \pi \times 16=\frac{16}{9}\times \pi$

$\pi=3.14$

=>$\frac{16}{9}\times 3.14=5.58222...\approx 5.58$

Is this right?

Total circumference =  pi d = 16 pi

 this is a fraction of total    40/360  * 16pi =    16/9 pi =~ 5.59  METERS    ( you only get 1/2 credit if you leave units off!)