Given sequence (18 elements): L, X, J, K, I, L, U, A, 5, 9, H, 2, T, %, 9, @,…
2023
Given sequence (18 elements):
L, X, J, K, I, L, U, A, 5, 9, H, 2, T, %, 9, @, 1, #
If the first half of the sequence (the first 9 elements) is moved to the end of the second half (the last 9 elements), keeping the internal order of each half unchanged, which element will come 7 positions to the left of the 5th element from the right end of the new sequence?
Answer: D. @ — Concept: In a sequence-rearrangement problem, first construct the new sequence exactly as described, then convert a position counted from the right end into a…
- A.
#
- B.
1
- C.
U
- D.
@
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Show answer & explanation
Correct answer: D
Concept: In a sequence-rearrangement problem, first construct the new sequence exactly as described, then convert a position counted from the right end into a position counted from the left end using (total count − position from right + 1), and apply any further left/right offset by subtracting or adding it from that reference position.
Application:
Total elements N = 18, so each half has 9 elements.
Original sequence: L, X, J, K, I, L, U, A, 5, 9, H, 2, T, %, 9, @, 1, #.
Moving the first 9 elements (L, X, J, K, I, L, U, A, 5) to the end gives the new sequence: 9, H, 2, T, %, 9, @, 1, #, L, X, J, K, I, L, U, A, 5.
The 5th element from the right end is at position 18 − 5 + 1 = 14, which is I.
7 positions to the left of position 14 is 14 − 7 = 7.
Counting to position 7 in the new sequence (9, H, 2, T, %, 9, @) gives @.
Cross-check: Position 7 from the left in an 18-element sequence is the (18 − 7 + 1) = 12th element from the right. Counting backward from the right end of the new sequence — 5, A, U, L, I, K, J, X, L, #, 1, @ — the 12th element is @, confirming the result.
@ is the required element 7 positions to the left of the 5th element from the right end.