\section*{Task 2 - 021212}

A fishery production cooperative wants to know how many fish of a certain species are approximately in a small lake. To this end, 30 fish of this species are caught, marked, and returned to the lake. The next day, 52 fish of the same species are caught, among which 4 are marked.

How many fish of this species were approximately in the lake? (Justification!)
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Since we have no further information, we must assume that the 52 fish from the second catch represent a representative sample of the total fish population in the lake. Accordingly, \(\frac{4}{52}\) of the fish (in the entire lake!) are marked, which means every 13th fish.

In total, there are approximately \(13 \cdot 30=390\) fish in this lake.