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Solution

The series is a G.P. with first term $\dfrac13$ and ratio $\dfrac13$. Sum $=\dfrac{\frac13}{1-\frac13}=\dfrac12$ So $y=0.36\log_{0.25}\left(\dfrac12\right)$ $\log_{0.25}\left(\dfrac12\right)=\dfrac{\log(1/2)}{\log(1/4)}=\dfrac{-1}{-2}=\dfrac12$ Hence $y=0.36\times\dfrac12=0.18$ Answer: $\boxed{0.18}$