Seven members in a row – who sits exactly in the middle? Constraints (left-to-right ordering): C is left of B but right of D (D … C … B). A is right of B. F is right of E but left of D (E … F … D). H is left of E.
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AC
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BD
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CE
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DF
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EB
Answer
Correct Answer: D
Explanation
Introduction / Context:We have seven distinct members with multiple “to the left/right of” constraints. The goal is to determine who occupies the central (4th) position when everyone is arranged left to right.
Given Data / Assumptions:
- D … C … B (C is between D and B, with C left of B).
- A is to the right of B ⇒ B … A.
- E … F … D (F is right of E but left of D).
- H is left of E ⇒ H … E.
Concept / Approach:Chain the inequalities to form one consistent sequence. From E … F … D and H … E, we get H … E … F … D. From D … C … B and B … A, extend to the right: … D … C … B … A.
Step-by-Step Solution:
Concatenate: H – E – F – D – C – B – A.This satisfies all four constraints simultaneously.In a 7-seat order, the middle (4th) position is occupied by D.Verification / Alternative check:Any attempt to move D left of F breaks “F left of D”; moving C left of D breaks “D left of C”; placing A to the left of B breaks “A right of B.”
Why Other Options Are Wrong:C, E, F are not at the 4th position in any arrangement that honors all constraints.
Common Pitfalls:Not chaining all relations together and overlooking that the set H, E, F, D must precede C, B, A in that order.
Final Answer:D