Answer :

[tex]a^\frac{m}{n}=\sqrt[n]{a^m}\\---------------\\\\(-0.008)^\frac{2}{3}=\sqrt[3]{(-0.008)^2}=\left(\sqrt[3]{-0.008}\right)^2=\left(-0.2\right)^2=0.04[/tex]
0.008 is actually 8/1000, therefore -0.008 is -8/1000.

[tex] ( \frac{-8}{1000} )^{ \frac{2}{3} } = \sqrt[3]{( \frac{-8}{1000})^{2} } = \sqrt[3]{ \frac{64}{1,000,000} }= \frac{4}{100}=0.04= \frac{2}{50}= \frac{1}{25} [/tex]