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MathNet 2018-part-07 — 177 problems (EN–VI) Question 103

Math Olympiad Vault · MathNet 2018-part-07 — 177 problems (EN–VI)

Question 103

There are $2018$ frogs in a pool and there is $1$ frog on the shore. In each time-step thereafter, one random frog moves position. If it was in the pool, it jumps to the shore, and vice versa. Find the expected number of time-steps before all frogs are in the pool for the first time.