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HMMT November 2017 H9

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New this year at HMNT: the exciting game of RNGR N G baseball! In RNG baseball, a team of infinitely many people play on a square field, with a base at each vertex; in particular, one of the bases is called the home base. Every turn, a new player stands at home base and chooses a number nn uniformly at random from {0,1,2,3,4}\{0,1,2,3,4\}. Then, the following occurs:

  • If n>0n>0, then the player and everyone else currently on the field moves (counterclockwise) around the square by nn bases. However, if in doing so a player returns to or moves past the home base, he/she leaves the field immediately and the team scores one point.
  • If n=0n=0 (a strikeout), then the game ends immediately; the team does not score any more points.

What is the expected number of points that a given team will score in this game?

Dataset text NuminaMath olympiads. Quoted with source.

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\frac{409}{125}

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