Problem #PRU-65307

Problems Probability and statistics Probability theory Discrete distribution

Problem

In the Valley of the Five Lakes there are five identical lakes, some of which are connected by streams (in the image, dotted lines denote the possible “routes” of streams). Small carps are born only in lake \(S\). While the carp is growing up, it passes exactly four times from one lake to another by some stream (the carp chooses a stream at random), and then it remains in the lake in which it ended up. Of every thousand carps, an average of 375 remain in lake \(S\), and the rest remain in lake \(B\), no one else lives in the other lakes. Determine how many streams there are in the Valley of the Five Lakes.