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Problem 300

Combinatorics Difficulty 2.4 Multiple choice CEMC Gauss (Grade 8) · Canada · 2026

Abel, Brock, Callie, Duan, and Edith are sitting around a
circular table. Brock sits in the chair between Abel and Duan. Edith is
not beside Duan. Who is sitting to Edith's immediate left and right?

Pick one

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Official solution

Brock is seated in the chair between Abel and Duan, as shown in
Figure 1.

Edith is not beside Duan, and thus must be beside Abel, as shown in
Figure 2.

Callie must be seated in the final seat. Therefore, Abel and Callie are
seated to Edith's immediate left and right, as shown in Figure 3.

Confirm for yourself that switching the positions of Abel and Duan in
each figure results in Edith and Callie switching positions in Figure 3,
but does not change the final result.

[[IMAGE0]]
Figure 1

[[IMAGE1]]
Figure 2

[[IMAGE2]]
Figure 3

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.