Five friends on a bench – identify the two extremes: Rules: C is to the left of A, and A is to the left of B (C … A … B). Also, D is to the right of B and to the left of E (B … D … E). Who are at the two extreme ends (leftmost and rightmost)?
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AC and E
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BA and D
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CB and D
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DD and E
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EA and B
Answer
Correct Answer: C and E
Explanation
Introduction / Context:We are given two chains that must be merged into a single left-to-right order. The task is to identify the extreme-left and extreme-right persons.
Given Data / Assumptions:
- C … A … B (A is to the left of B but to the right of C).
- B … D … E (D is to the right of B but to the left of E).
- Distinct persons A, B, C, D, E sit in one row from left to right.
Concept / Approach:Merge the two constraints by overlapping the shared person B and preserving order on each side. The combined consistent sequence becomes C – A – B – D – E.
Step-by-Step Solution:
Start with C – A – B from the first rule.Append D to the right of B and E to the right of D to satisfy the second rule.The final arrangement is C (leftmost), A, B, D, E (rightmost).Verification / Alternative check:Any reordering that changes the relative positions (e.g., placing D left of B or A right of B) will violate at least one rule.
Why Other Options Are Wrong:Pairs that do not include C on the far left or E on the far right contradict the merged chain.
Common Pitfalls:Misreading “left of” and “right of” or trying to place D to the left of B.
Final Answer:C and E