Directions: Read the information and answer the question. Nine boxes named A,…
2025
Directions: Read the information and answer the question.
Nine boxes named A, B, C, D, E, F, G, H, and I are stacked one above another. Box F is immediately above Box G. There are exactly three boxes between Box A and Box B. Two boxes are between Box C and Box D, and Box D is immediately above Box B. Box E is immediately above Box A. There is exactly one box between Box H and Box I, and Box I is somewhere below Box H.
Which box is kept at the lowest position?
- A.
H
- B.
I
- C.
G
- D.
F
- E.
C
Attempted by 1 students.
Show answer & explanation
Correct answer: B
CONCEPT: In a vertical-stack puzzle, treat every clue as either a fixed-gap relation or an immediate-neighbor relation. Build only arrangements that satisfy all fixed gaps, then place the remaining adjacent pairs; any case that leaves no legal space for a required pair is eliminated.
APPLICATION:
Use the A-B gap: exactly three boxes between A and B means the two boxes must be separated by four levels, so both possible vertical orders are checked.
Attach D immediately above B. The clue about C and D then forces C to be two levels away from D, keeping only cases where that gap is possible.
Place E immediately above A. Any case where E cannot sit directly above A is removed.
Place H and I with exactly one box between them and I below H. This removes the branch that leaves no valid H-I placement.
Place F immediately above G in the only remaining adjacent levels. The final top-to-bottom order becomes E, A, F, G, D, B, H, C, I.
Position from top | Box |
|---|---|
1 | E |
2 | A |
3 | F |
4 | G |
5 | D |
6 | B |
7 | H |
8 | C |
9 | I |
CROSS-CHECK: The final stack satisfies every clue: F is immediately above G, A and B have three boxes between them, C and D have two boxes between them, D is immediately above B, E is immediately above A, and H and I have one box between them with I below H.
Result: the lowest box is I.