Difficulty: Medium
Correct Answer: B
Explanation:
Introduction / Context:Indexing problems in reversed sequences are common in verbal reasoning. A direct reversal and recount is possible but time-consuming. A position-mapping shortcut avoids rewriting the sequence and reduces errors.
Given Data / Assumptions:
Concept / Approach:In the reversed sequence, the element 8 to the right of the 7th from the left is the element at position 7 + 8 = 15 from the left (in the reversed array). The 15th-from-left in the reversed sequence equals the 15th-from-right in the original sequence. If the original has N elements, the k-th from right is at position N - k + 1 from the left.
Step-by-Step Solution:
1) Compute the target index in the reversed sequence: 7 + 8 = 15.2) Map to the original sequence: 15th from left in reversed = 15th from right in original.3) Total N = 32. The 15th from right is at index N - 15 + 1 = 18 from the left in the original.4) Count to the 18th letter in the original sequence: 1 C, 2 E, 3 B, 4 A, 5 C, 6 D, 7 B, 8 C, 9 D, 10 A, 11 C, 12 E, 13 B, 14 E, 15 D, 16 C, 17 A, 18 B.5) The 18th letter is B.Verification / Alternative check:You can explicitly reverse the sequence and count to the 15th position; it will also be B, confirming the mapping shortcut.
Why Other Options Are Wrong:
Common Pitfalls:Forgetting that moving 8 to the right after selecting the 7th adds to 15 total, or misapplying the N - k + 1 mapping. Another common mistake is switching to 0-based counting mid-way.
Final Answer:B
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