Answer:
4√10 ( option C)
[tex]solution \\ from \: the \: geometric \: mean \: therem \\ \frac{8}{m} = \frac{m}{20} \\ or m \times m = 20 \times 8 \\ or \: {m}^{2} = 180 \\ or \: m = \sqrt{180} \\ m = 4 \sqrt{10} [/tex]
Hope this helps...
Good luck on your assignment
