MathDB
2022 A Individual #17

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April 28, 2022
2022 A Individual

Problem Statement

Jane and Jena sit at non-adjacent chairs of a four-chair circular table. In a turn, one person can move to an adjacent chair without a person. Jane moves in the first turn, and alternates with Jena afterwards. In how many ways can Jena be adjacent to Jane after nine moves?
<spanclass=latexbold>(A)</span>16<spanclass=latexbold>(B)</span>18<spanclass=latexbold>(C)</span>32<spanclass=latexbold>(D)</span>162<spanclass=latexbold>(E)</span>512<span class='latex-bold'>(A) </span>16\qquad<span class='latex-bold'>(B) </span>18\qquad<span class='latex-bold'>(C) </span>32\qquad<span class='latex-bold'>(D) </span>162\qquad<span class='latex-bold'>(E) </span>512