The table below shows the number of lakes in California classified by alkalinity and depth.

$$ \small \begin{array} {|l|} \hline \\ \text{Depth class} \\ \hline \text{Shallow} \\ \hline \text{Moderate} \\ \hline \text{Deep} \\ \hline \text{Total} \\ \hline \end{array} \begin{array} {c c c c|} \hline \hspace{1.5em}& \hspace{1.5em} \text{Alkalinity} & \hspace{-1.5em} \text{class} & \hspace{4em} \\ \hline \text{Low} & \text{Medium} & \text{High} & \text{Total} \\ \hline 372 & 450 & 825 & 1{,}647 \\ \hline 366& 512 & 255 & 1{,}133\\ \hline 91 & 111& 123 & 325 \\ \hline 829 & 1{,}073 & 1{,}203 & 3{,}105\\ \hline \end{array} $$

If a lake has medium alkalinity, which of the following is closest to the probability that the lake also has a moderate or deep depth?

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We are looking for the following:

$$ \frac{\text{moderate or deep lake}}{\text{medium alkalinity lake}} $$ $$ \begin{array} {|l|} \hline \\ \text{Depth class} \\ \hline \text{Shallow} \\ \hline \colorbox{yellow}{\text{Moderate}} \\ \hline \colorbox{yellow}{\text{Deep}} \\ \hline \text{Total} \\ \hline \end{array} \begin{array} {c c c c|} \hline \hspace{1.5em}& \hspace{1.5em} \text{Alkalinity} & \hspace{-1.5em} \text{class} & \hspace{4em} \\ \hline \text{Low} & \colorbox{yellow}{\text{Medium}} & \text{High} & \text{Total} \\ \hline 372 & 450 & 825 & 1{,}647 \\ \hline 366& \colorbox{aqua}{$512$} & 255 & 1{,}133\\ \hline 91 & \colorbox{aqua}{$111$}& 123 & 325 \\ \hline 829 & \colorbox{chartreuse}{$1{,}073$} & 1{,}203 & 3{,}105\\ \hline \end{array} $$

Out of the 1,073 lakes, 512 and 111 are moderate or deep.

$$ \frac{\text{moderate or deep lake}}{\text{medium alkalinity lake}} $$ $$ \frac{512+111}{1{,}073} $$ $$ \approx \boxed{0.58} $$