Box/Stack Puzzles - Advanced Level: horizontal stacking ADVANCED

Quick competitive exam prep session: 20 advanced-level box/stack puzzles questions. Worksheet 27 of 30 - Focus: horizontal stacking. Practice stacking logic, box hierarchy, stack puzzles with instant feedback. Great for advanced students needing complex scenarios and multi-step problems practice.

📝 Worksheet 27 of 30 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Advanced level

What you'll learn in this worksheet:
Your progress through Box/Stack Puzzles
Worksheet 27 of 30 (90% complete)

Question 1

Initially, five boxes A, B, C, D, and E are in Stack 1 (positions 1-5, bottom to top): A at position 1, B at 2, C at 3, D at 4, E at 5. A series of operations is performed: Operation 1: Move the top box of Stack 1 to a new Stack 2 Operation 2: Move the box at position 2 of Stack 1 to top of Stack 2 Operation 3: Move the top box of Stack 1 to top of Stack 2 After these operations, which box is at the bottom of Stack 2?
Step-by-step Solution:
1. Initial State:
- Stack 1 (bottom to top): A(1), B(2), C(3), D(4), E(5)
- Stack 2: Empty

2. Operation 1: Move top box of Stack 1 to Stack 2
- Remove E from Stack 1 (was at position 5)
- Stack 1 after: A(1), B(2), C(3), D(4)
- Stack 2 after: E(1)

3. Operation 2: Move box at position 2 of Stack 1 to top of Stack 2
- Box at position 2 is B
- Remove B from Stack 1
- Stack 1 after: A(1), C(2), D(3) [positions renumber]
- Stack 2 after: E(1), B(2) [B placed on top]

4. Operation 3: Move top box of Stack 1 to top of Stack 2
- Top box of Stack 1 is D (position 3)
- Remove D from Stack 1
- Stack 1 after: A(1), C(2)
- Stack 2 after: E(1), B(2), D(3) [D placed on top]

5. Final Stack 2 (bottom to top): E, B, D

6. Answer: Box E is at the bottom of Stack 2

Question 2

Five boxes K, L, M, N, and O are stacked vertically (positions 1 to 5 from bottom to top). Each box has a unique weight from the set: 15kg, 25kg, 35kg, 45kg, and 55kg. Stacking rule: Heavier boxes must be placed below lighter boxes. Conditions: - Box O is at the bottom (position 1) - Box K is at the top (position 5) - Box N's weight is greater than Box M's weight, but less than 50kg - The box immediately above Box M has weight less than 30kg - Box L's weight is exactly 25kg What is the weight of Box N?
Step-by-step Solution:

1. Apply stacking rule: Heavier below lighter
- So weights must decrease from bottom to top
- Position 1 (bottom) = heaviest
- Position 5 (top) = lightest

2. Fixed positions:
- Position 1 = Box O (given)
- Position 5 = Box K (given)
- Therefore: O is heaviest (55kg), K is lightest (15kg)

3. Box L's weight is exactly 25kg
- So L must be at position 4 (since 25kg is second lightest)
- Position 4 = L (25kg)

4. Remaining boxes: M and N for positions 2 and 3
- Remaining weights: 35kg and 45kg

5. Constraint: N > M (in weight)
- So N must be heavier than M
- Therefore: N at position 2 (45kg), M at position 3 (35kg)

6. Verify additional constraints:
- "Box N's weight is less than 50kg" → 45kg < 50kg ✓
- "Box immediately above M has weight < 30kg"
- M at position 3 → box above is position 4 = L (25kg) < 30kg ✓

7. Final stack (bottom to top):
- Position 1: O (55kg)
- Position 2: N (45kg)
- Position 3: M (35kg)
- Position 4: L (25kg)
- Position 5: K (15kg)

8. Answer: Box N weighs 45kg

Verification: All conditions satisfied ✓

Question 3

Eight boxes A, B, C, D, E, F, G, and H are arranged in two vertical stacks (Stack 1 and Stack 2), with 4 boxes in each stack. Positions are numbered 1 to 4 from bottom to top in each stack. - Box A is at the top of Stack 1 - Box B is in Stack 2 at position 2 - Box C is immediately below box A in Stack 1 - Box D is at the same position in Stack 2 as box C in Stack 1 - Box E is at the bottom of Stack 1 - Box F is immediately above box D in Stack 2 Which box is at the bottom of Stack 2?
Step-by-step Solution:

1. Stack 1 Analysis:
- Box A at top → Stack1[4] = A
- Box C immediately below A → Stack1[3] = C
- Box E at bottom → Stack1[1] = E
- Remaining box G goes to Stack1[2]

Stack 1 (bottom to top): E, G, C, A

2. Stack 2 Analysis:
- Box B at position 2 → Stack2[2] = B
- Box D at same position as C in Stack1 (position 3) → Stack2[3] = D
- Box F immediately above D → Stack2[4] = F
- Remaining box H goes to Stack2[1] (bottom)

Stack 2 (bottom to top): H, B, D, F

3. Answer: Box H is at the bottom of Stack 2

Verification: All constraints satisfied ✓

Question 4

Five boxes P, Q, R, S, and T of different sizes are stacked vertically (positions 1 to 5 from bottom to top). The stacking rule is: larger boxes must be placed below smaller boxes. Size relationships: - Box P is larger than box Q but smaller than box R - Box S is the smallest - Box T is larger than box R - Box Q is larger than box S If box S is removed from the stack, which box will be at position 4 (counting from the bottom)?
Step-by-step Solution:

1. Establish size relationships:
- P > Q and R > P → So R > P > Q
- S is smallest → S is less than all others
- T > R
- Q > S

2. Combine all inequalities:
- From T > R and R > P > Q, we get: T > R > P > Q
- From Q > S, we get: T > R > P > Q > S

3. Complete size order (largest to smallest):
T > R > P > Q > S

4. Apply stacking rule (larger below smaller):
- Position 1 (bottom): T (largest)
- Position 2: R
- Position 3: P
- Position 4: Q
- Position 5 (top): S (smallest)

5. Remove box S from position 5:

6. Remaining stack (4 boxes):
- Position 1: T
- Position 2: R
- Position 3: P
- Position 4: Q

7. Answer: Box Q is at position 4

Verification:
- T > R ✓ (pos1 vs pos2)
- R > P ✓ (pos2 vs pos3)
- P > Q ✓ (pos3 vs pos4)
- Q > S ✓ (pos4 vs pos5 before removal)

Question 5

Six boxes A, B, C, D, E, and F are stacked vertically (positions 1 to 6 from bottom to top). The box at stack position n is then placed at seat position n in a circular arrangement of 6 chairs (seats 1 to 6 in clockwise order). Conditions: - Box A is at the bottom of the stack (position 1) - Box B is at the top of the stack (position 6) - Box C is immediately above box D in the stack - In the circular arrangement, box E is opposite box F - Box C is at seat 4 in the circular arrangement Which box sits opposite box A in the circular arrangement?
Step-by-step Solution:

1. Stack to Circle mapping:
- Seat n = Box at stack position n

2. Fixed assignments:
- Stack pos1 = A → Seat1 = A
- Stack pos6 = B → Seat6 = B
- Box C at seat4 (given) → Stack pos4 = C

3. Box C immediately above Box D in stack:
- C at pos4 → D must be at pos3
- Therefore: Stack pos3 = D

4. Remaining positions in stack: pos2 and pos5 for boxes E and F
- Stack pos2 → Seat2
- Stack pos5 → Seat5

5. In circular arrangement, E opposite F:
- In a 6-seat circle, opposite pairs are: (1,4), (2,5), (3,6)
- Seat1 = A, Seat4 = C, Seat3 = D, Seat6 = B
- For E and F to be opposite, they must occupy seats (2,5)
- Therefore: Seat2 and Seat5 = E and F (in some order)

6. Determine which is which:
- Seat2 = Stack pos2 = either E or F
- Seat5 = Stack pos5 = the other one
- Both arrangements are valid

7. Complete the arrangement:
- Stack: pos1=A, pos2=E/F, pos3=D, pos4=C, pos5=F/E, pos6=B
- Circle: Seat1=A, Seat2=E/F, Seat3=D, Seat4=C, Seat5=F/E, Seat6=B

8. Find box opposite A:
- A is at Seat1
- Opposite seat to Seat1 is Seat4 (since 1+3=4)
- Seat4 = C

9. Answer: Box C sits opposite Box A

Final verification:
- A at bottom ✓
- B at top ✓
- C(pos4) immediately above D(pos3) ✓
- E and F at seats 2 and 5 (opposite) ✓
- C at seat4 ✓

Answer: Box C

Question 6

Five books A, B, C, D, and E are arranged horizontally on a shelf from left to right (positions 1 to 5). Given conditions: - Book A is at the leftmost position - Book B is immediately to the right of Book C - Book D is at the rightmost position - Book E is at position 4 Which book is at position 3?
Step-by-step Solution:

1. Fixed positions:
- Position 1 = A (leftmost)
- Position 5 = D (rightmost)
- Position 4 = E

2. Remaining positions: 2 and 3 for books B and C

3. "B is immediately to the right of C":
- They must be consecutive with C on left, B on right
- Therefore: C at position 2, B at position 3

4. Final arrangement:
- Position 1: A
- Position 2: C
- Position 3: B
- Position 4: E
- Position 5: D

5. Answer: Book B is at position 3

Verification: All conditions satisfied ✓

Question 7

Initially, five boxes A, B, C, D, and E are in Stack 1 (positions 1-5, bottom to top): A at position 1, B at 2, C at 3, D at 4, E at 5. A series of operations is performed: Operation 1: Move the top box of Stack 1 to a new Stack 2 Operation 2: Move the box at position 2 of Stack 1 to top of Stack 2 Operation 3: Move the top box of Stack 1 to top of Stack 2 After these operations, which box is at the bottom of Stack 2?
Step-by-step Solution:
1. Initial State:
- Stack 1 (bottom to top): A(1), B(2), C(3), D(4), E(5)
- Stack 2: Empty

2. Operation 1: Move top box of Stack 1 to Stack 2
- Remove E from Stack 1 (was at position 5)
- Stack 1 after: A(1), B(2), C(3), D(4)
- Stack 2 after: E(1)

3. Operation 2: Move box at position 2 of Stack 1 to top of Stack 2
- Box at position 2 is B
- Remove B from Stack 1
- Stack 1 after: A(1), C(2), D(3) [positions renumber]
- Stack 2 after: E(1), B(2) [B placed on top]

4. Operation 3: Move top box of Stack 1 to top of Stack 2
- Top box of Stack 1 is D (position 3)
- Remove D from Stack 1
- Stack 1 after: A(1), C(2)
- Stack 2 after: E(1), B(2), D(3) [D placed on top]

5. Final Stack 2 (bottom to top): E, B, D

6. Answer: Box E is at the bottom of Stack 2

Question 8

Seven boxes A, B, C, D, E, F, and G are stacked vertically (positions 1 to 7 from bottom to top). Given conditions: - Box C is at position 3 - The product of the positions of boxes C and D is 12 - Box E is at a prime-numbered position - Box F is at a position that is 5 more than twice the position of box G - The sum of the positions of boxes A and B is 8, with box A below box B - Box D is at an even-numbered position - Box G is at an odd-numbered position What is the position of box A?
Step-by-step Solution:

1. Start with fixed information:
- Position 3 = C (given)

2. Product condition: pos(C) × pos(D) = 12
- 3 × pos(D) = 12
- pos(D) = 4

3. Box D is at even position: 4 is even ✓

4. Prime position for Box E: Prime positions are 2, 3, 5, 7
- Position 3 is C, so E can be at 2, 5, or 7

5. F and G relationship: pos(F) = 5 + 2 × pos(G)
- Possible (G, F) pairs: (1,7), (2,9-invalid), (3,11-invalid)
- Therefore: G at 1, F at 7

6. Sum condition: pos(A) + pos(B) = 8, with pos(A) < pos(B) (A below B)
- Possible pairs: (1,7), (2,6), (3,5)
- Position 1 is G, position 3 is C, position 7 is F
- Therefore: (1,7) and (3,5) invalid
- Only possibility: A at 2, B at 6

7. Box E must be at prime position:
- Remaining position after placing A(2), B(6), C(3), D(4), F(7), G(1)
- Only position left is 5 for E
- 5 is prime ✓

8. Final arrangement (bottom to top):
- Position 1: G
- Position 2: A
- Position 3: C
- Position 4: D
- Position 5: E
- Position 6: B
- Position 7: F

9. Answer: Box A is at position 2

Verification of all conditions:
- C at position 3 ✓
- C(3) × D(4) = 12 ✓
- E at position 5 (prime) ✓
- F(7) = 5 + 2×G(1) ✓
- A(2) + B(6) = 8, A below B (2 < 6) ✓
- D at even position (4) ✓
- G at odd position (1) ✓

Answer: Position 2

Question 9

Eight boxes A, B, C, D, E, F, G, and H are arranged in two vertical stacks (Stack 1 and Stack 2), with 4 boxes in each stack. Positions are numbered 1 to 4 from bottom to top in each stack. - Box A is at the top of Stack 1 - Box B is in Stack 2 at position 2 - Box C is immediately below box A in Stack 1 - Box D is at the same position in Stack 2 as box C in Stack 1 - Box E is at the bottom of Stack 1 - Box F is immediately above box D in Stack 2 Which box is at the bottom of Stack 2?
Step-by-step Solution:

1. Stack 1 Analysis:
- Box A at top → Stack1[4] = A
- Box C immediately below A → Stack1[3] = C
- Box E at bottom → Stack1[1] = E
- Remaining box G goes to Stack1[2]

Stack 1 (bottom to top): E, G, C, A

2. Stack 2 Analysis:
- Box B at position 2 → Stack2[2] = B
- Box D at same position as C in Stack1 (position 3) → Stack2[3] = D
- Box F immediately above D → Stack2[4] = F
- Remaining box H goes to Stack2[1] (bottom)

Stack 2 (bottom to top): H, B, D, F

3. Answer: Box H is at the bottom of Stack 2

Verification: All constraints satisfied ✓

Question 10

Five boxes K, L, M, N, and O are stacked vertically (positions 1 to 5 from bottom to top). Each box has a unique weight from the set: 15kg, 25kg, 35kg, 45kg, and 55kg. Stacking rule: Heavier boxes must be placed below lighter boxes. Conditions: - Box O is at the bottom (position 1) - Box K is at the top (position 5) - Box N's weight is greater than Box M's weight, but less than 50kg - The box immediately above Box M has weight less than 30kg - Box L's weight is exactly 25kg What is the weight of Box N?
Step-by-step Solution:

1. Apply stacking rule: Heavier below lighter
- So weights must decrease from bottom to top
- Position 1 (bottom) = heaviest
- Position 5 (top) = lightest

2. Fixed positions:
- Position 1 = Box O (given)
- Position 5 = Box K (given)
- Therefore: O is heaviest (55kg), K is lightest (15kg)

3. Box L's weight is exactly 25kg
- So L must be at position 4 (since 25kg is second lightest)
- Position 4 = L (25kg)

4. Remaining boxes: M and N for positions 2 and 3
- Remaining weights: 35kg and 45kg

5. Constraint: N > M (in weight)
- So N must be heavier than M
- Therefore: N at position 2 (45kg), M at position 3 (35kg)

6. Verify additional constraints:
- "Box N's weight is less than 50kg" → 45kg < 50kg ✓
- "Box immediately above M has weight < 30kg"
- M at position 3 → box above is position 4 = L (25kg) < 30kg ✓

7. Final stack (bottom to top):
- Position 1: O (55kg)
- Position 2: N (45kg)
- Position 3: M (35kg)
- Position 4: L (25kg)
- Position 5: K (15kg)

8. Answer: Box N weighs 45kg

Verification: All conditions satisfied ✓

Question 11

Five boxes P, Q, R, S, and T are in a stack numbered 1 to 5 from TOP to BOTTOM (1 is topmost, 5 is bottommost). Given conditions: - Box P is at the top (position 1) - Box Q is at the bottom (position 5) - Box S is immediately above box T - Box R is at position 4 Which box is at position 4 from the top?
Step-by-step Solution:

1. Understanding the numbering system:
- Position 1 = TOP
- Position 5 = BOTTOM

2. Fixed positions:
- Position 1 = P
- Position 5 = Q
- Position 4 = R

3. Remaining positions: 2 and 3 for boxes S and T

4. "S is immediately above T":
- They must occupy consecutive positions with S above T
- Therefore: S at position 2, T at position 3

5. Final arrangement (top to bottom):
- Position 1: P
- Position 2: S
- Position 3: T
- Position 4: R
- Position 5: Q

6. Answer: Box R is at position 4

Verification: All conditions satisfied ✓

Question 12

Five boxes A, B, C, D, and E are stacked one above another (bottom to top numbered 1 to 5). Box C is at position 3. Box A is immediately above box B. Box D is at the bottom. Which box is at the top of the stack?
Step-by-step Solution:

1. Create position table (1 = bottom, 5 = top)

2. Direct assignments:
- Box D is at bottom → Position 1 = D
- Box C is at position 3 → Position 3 = C

3. Key constraint: Box A is immediately above Box B
- They must occupy consecutive positions: (1,2), (2,3), (3,4), or (4,5)
- Position 1 is D, Position 3 is C → only (4,5) is available
- Therefore: Position 4 = B, Position 5 = A

4. Remaining box: E goes to Position 2

5. Final stack (bottom to top):
- Position 1: D
- Position 2: E
- Position 3: C
- Position 4: B
- Position 5: A

6. Answer: Box A is at the top

Verification: All constraints satisfied ✓

Question 13

Seven boxes A, B, C, D, E, F, and G are stacked vertically (positions 1 to 7 from bottom to top). Given conditions: - Box C is at position 3 - The product of the positions of boxes C and D is 12 - Box E is at a prime-numbered position - Box F is at a position that is 5 more than twice the position of box G - The sum of the positions of boxes A and B is 8, with box A below box B - Box D is at an even-numbered position - Box G is at an odd-numbered position What is the position of box A?
Step-by-step Solution:

1. Start with fixed information:
- Position 3 = C (given)

2. Product condition: pos(C) × pos(D) = 12
- 3 × pos(D) = 12
- pos(D) = 4

3. Box D is at even position: 4 is even ✓

4. Prime position for Box E: Prime positions are 2, 3, 5, 7
- Position 3 is C, so E can be at 2, 5, or 7

5. F and G relationship: pos(F) = 5 + 2 × pos(G)
- Possible (G, F) pairs: (1,7), (2,9-invalid), (3,11-invalid)
- Therefore: G at 1, F at 7

6. Sum condition: pos(A) + pos(B) = 8, with pos(A) < pos(B) (A below B)
- Possible pairs: (1,7), (2,6), (3,5)
- Position 1 is G, position 3 is C, position 7 is F
- Therefore: (1,7) and (3,5) invalid
- Only possibility: A at 2, B at 6

7. Box E must be at prime position:
- Remaining position after placing A(2), B(6), C(3), D(4), F(7), G(1)
- Only position left is 5 for E
- 5 is prime ✓

8. Final arrangement (bottom to top):
- Position 1: G
- Position 2: A
- Position 3: C
- Position 4: D
- Position 5: E
- Position 6: B
- Position 7: F

9. Answer: Box A is at position 2

Verification of all conditions:
- C at position 3 ✓
- C(3) × D(4) = 12 ✓
- E at position 5 (prime) ✓
- F(7) = 5 + 2×G(1) ✓
- A(2) + B(6) = 8, A below B (2 < 6) ✓
- D at even position (4) ✓
- G at odd position (1) ✓

Answer: Position 2

Question 14

Seven positions (1 to 7, bottom to top) form a vertical stack. Only five boxes P, Q, R, S, and T are placed; the remaining two positions are empty. Conditions: - Box Q is at the top (position 7) - Box P is at the bottom (position 1) - Box R and Box S have exactly two entities (boxes or empty slots) between them - One empty slot is at position 2 - Box T is immediately above the second empty slot At which position is box T located?
Step-by-step Solution:

1. Fixed positions:
- Position 1 = P (bottom)
- Position 7 = Q (top)
- Position 2 = Empty (first empty slot - given)

2. Remaining positions to fill: 3, 4, 5, 6
- Need to place: R, S, T, and the second empty slot

3. Box T is immediately above the second empty slot:
- Let the second empty slot be at position X
- Then T must be at position X + 1
- Possible X values: 3, 4, 5 (since X+1 ≤ 7 and X+1 cannot be 7 because Q is there)
- X cannot be 6 because T would need to be at 7, but position 7 is Q

4. Try X = 3 (second empty at 3, T at 4):
- Remaining positions: 5 and 6 for R and S
- R and S at 5 and 6 → they are adjacent (0 entities between them)
- This violates "exactly two entities between R and S" ✗

5. Try X = 4 (second empty at 4, T at 5):
- Remaining positions: 3 and 6 for R and S
- Between positions 3 and 6: we have positions 4 and 5
- Position 4 = Empty, Position 5 = T
- That's exactly 2 entities between R and S ✓
- This works!

6. Try X = 5 (second empty at 5, T at 6):
- Remaining positions: 3 and 4 for R and S
- Between positions 3 and 4: no positions between them (0 entities)
- This violates the constraint ✗

7. Therefore, the only valid arrangement is X = 4:
- Position 3: R
- Position 4: Empty (second empty)
- Position 5: T
- Position 6: S

8. Final arrangement (bottom to top):
- Position 1: P
- Position 2: Empty
- Position 3: R
- Position 4: Empty
- Position 5: T
- Position 6: S
- Position 7: Q

9. Verification of all conditions:
- Q at top (7) ✓
- P at bottom (1) ✓
- R at 3, S at 6 → between them: positions 4 (Empty) and 5 (T) → exactly 2 entities ✓
- Empty slot at position 2 ✓
- T at position 5 is immediately above second empty at position 4 ✓

10. Answer: Box T is at position 5

Final Answer: Position 5

Question 15

Seven boxes A, B, C, D, E, F, and G are stacked vertically (positions 1 to 7 from bottom to top). Given conditions: - Box C is at position 3 - The product of the positions of boxes C and D is 12 - Box E is at a prime-numbered position - Box F is at a position that is 5 more than twice the position of box G - The sum of the positions of boxes A and B is 8, with box A below box B - Box D is at an even-numbered position - Box G is at an odd-numbered position What is the position of box A?
Step-by-step Solution:

1. Start with fixed information:
- Position 3 = C (given)

2. Product condition: pos(C) × pos(D) = 12
- 3 × pos(D) = 12
- pos(D) = 4

3. Box D is at even position: 4 is even ✓

4. Prime position for Box E: Prime positions are 2, 3, 5, 7
- Position 3 is C, so E can be at 2, 5, or 7

5. F and G relationship: pos(F) = 5 + 2 × pos(G)
- Possible (G, F) pairs: (1,7), (2,9-invalid), (3,11-invalid)
- Therefore: G at 1, F at 7

6. Sum condition: pos(A) + pos(B) = 8, with pos(A) < pos(B) (A below B)
- Possible pairs: (1,7), (2,6), (3,5)
- Position 1 is G, position 3 is C, position 7 is F
- Therefore: (1,7) and (3,5) invalid
- Only possibility: A at 2, B at 6

7. Box E must be at prime position:
- Remaining position after placing A(2), B(6), C(3), D(4), F(7), G(1)
- Only position left is 5 for E
- 5 is prime ✓

8. Final arrangement (bottom to top):
- Position 1: G
- Position 2: A
- Position 3: C
- Position 4: D
- Position 5: E
- Position 6: B
- Position 7: F

9. Answer: Box A is at position 2

Verification of all conditions:
- C at position 3 ✓
- C(3) × D(4) = 12 ✓
- E at position 5 (prime) ✓
- F(7) = 5 + 2×G(1) ✓
- A(2) + B(6) = 8, A below B (2 < 6) ✓
- D at even position (4) ✓
- G at odd position (1) ✓

Answer: Position 2

Question 16

Six boxes A, B, C, D, E, and F are arranged in a rack with 2 rows and 3 columns. Row 1 (top): Positions 1, 2, 3 (left to right) Row 2 (bottom): Positions 4, 5, 6 (left to right) Conditions: - Box A is in Row 1 - Box B is directly below box C - Box D is at position 4 (bottom-left) - Box E is to the immediate right of box A - Box F is in Row 2 but not below box A Which box is at position 5?
Step-by-step Solution:

1. Understand the layout:
- Row 1 (top): positions 1 (Col1), 2 (Col2), 3 (Col3)
- Row 2 (bottom): positions 4 (Col1), 5 (Col2), 6 (Col3)
- "Directly below" means same column, consecutive rows
- "Immediate right" means same row, adjacent columns

2. Direct assignment:
- Position 4 = D (given)

3. Place A and E:
- A in Row 1 (positions 1, 2, or 3)
- E immediately right of A
- Possible pairs: (A=1, E=2) or (A=2, E=3)
- Try A=1, E=2 first

4. Place B and C (B directly below C):
- Possible column pairs: (C at pos1, B at pos4), (C at pos2, B at pos5), (C at pos3, B at pos6)
- pos4 is already D, so (C=1, B=4) invalid
- Try C=3, B=6 (Column 3)

5. Place remaining box F:
- Available position: pos5
- F in Row 2 (pos5) and not below A
- A at pos1 (Col1), F at pos5 (Col2) → not below ✓

6. Final arrangement:
- Position 1: A
- Position 2: E
- Position 3: C
- Position 4: D
- Position 5: F
- Position 6: B

7. Answer: Box F is at position 5

Verification: All conditions satisfied ✓

Question 17

Five boxes P, Q, R, S, and T of different sizes are stacked vertically (positions 1 to 5 from bottom to top). The stacking rule is: larger boxes must be placed below smaller boxes. Size relationships: - Box P is larger than box Q but smaller than box R - Box S is the smallest - Box T is larger than box R - Box Q is larger than box S If box S is removed from the stack, which box will be at position 4 (counting from the bottom)?
Step-by-step Solution:

1. Establish size relationships:
- P > Q and R > P → So R > P > Q
- S is smallest → S is less than all others
- T > R
- Q > S

2. Combine all inequalities:
- From T > R and R > P > Q, we get: T > R > P > Q
- From Q > S, we get: T > R > P > Q > S

3. Complete size order (largest to smallest):
T > R > P > Q > S

4. Apply stacking rule (larger below smaller):
- Position 1 (bottom): T (largest)
- Position 2: R
- Position 3: P
- Position 4: Q
- Position 5 (top): S (smallest)

5. Remove box S from position 5:

6. Remaining stack (4 boxes):
- Position 1: T
- Position 2: R
- Position 3: P
- Position 4: Q

7. Answer: Box Q is at position 4

Verification:
- T > R ✓ (pos1 vs pos2)
- R > P ✓ (pos2 vs pos3)
- P > Q ✓ (pos3 vs pos4)
- Q > S ✓ (pos4 vs pos5 before removal)

Question 18

Five boxes A, B, C, D, and E are stacked one above another (bottom to top numbered 1 to 5). Box C is at position 3. Box A is immediately above box B. Box D is at the bottom. Which box is at the top of the stack?
Step-by-step Solution:

1. Create position table (1 = bottom, 5 = top)

2. Direct assignments:
- Box D is at bottom → Position 1 = D
- Box C is at position 3 → Position 3 = C

3. Key constraint: Box A is immediately above Box B
- They must occupy consecutive positions: (1,2), (2,3), (3,4), or (4,5)
- Position 1 is D, Position 3 is C → only (4,5) is available
- Therefore: Position 4 = B, Position 5 = A

4. Remaining box: E goes to Position 2

5. Final stack (bottom to top):
- Position 1: D
- Position 2: E
- Position 3: C
- Position 4: B
- Position 5: A

6. Answer: Box A is at the top

Verification: All constraints satisfied ✓

Question 19

Five books A, B, C, D, and E are arranged horizontally on a shelf from left to right (positions 1 to 5). Given conditions: - Book A is at the leftmost position - Book B is immediately to the right of Book C - Book D is at the rightmost position - Book E is at position 4 Which book is at position 3?
Step-by-step Solution:

1. Fixed positions:
- Position 1 = A (leftmost)
- Position 5 = D (rightmost)
- Position 4 = E

2. Remaining positions: 2 and 3 for books B and C

3. "B is immediately to the right of C":
- They must be consecutive with C on left, B on right
- Therefore: C at position 2, B at position 3

4. Final arrangement:
- Position 1: A
- Position 2: C
- Position 3: B
- Position 4: E
- Position 5: D

5. Answer: Book B is at position 3

Verification: All conditions satisfied ✓

Question 20

Nine boxes A, B, C, D, E, F, G, H, and I are arranged in three vertical stacks (Stack X, Y, Z) with 3 boxes each. Positions are numbered 1-3 from bottom to top in each stack. Conditions: - Box A is in Stack X at position 2 - Box B is at the same position in Stack Y as box C in Stack Z - Box C is at the top of Stack Z - Box D is in Stack X at the bottom - The sum of positions of box E in Stack Z and box F in Stack X equals 4 - Box G is immediately above box H in Stack Y - Box I is in Stack Z at position 2 In which stack and position is box E located?
Step-by-step Solution:

1. Direct assignments from given conditions:
- Stack X, position 2 = A
- Stack X, position 1 = D (bottom)
- Stack Z, position 3 = C (top)
- Stack Z, position 2 = I

2. From condition 2: B is at same position in Y as C in Z
- C at position 3 in Z → B at position 3 in Y

3. From condition 6: G immediately above H in Stack Y
- They must occupy consecutive positions: (1,2) or (2,3)
- Position 3 is B, so G and H must be at positions 1 and 2
- H at 1 (bottom), G at 2 (immediately above)

4. Stack Y so far:
- Position 1: H
- Position 2: G
- Position 3: B

5. Remaining boxes: E and F for Stacks X and Z
- Stack X has position 3 available
- Stack Z has position 1 available

6. From condition 5: pos(E in Z) + pos(F in X) = 4
- E can only be at Z position 1 (since Z positions 2 and 3 are I and C)
- F can only be at X position 3 (since X positions 1 and 2 are D and A)
- Therefore: 1 + 3 = 4 ✓

7. Final arrangements:
- Stack X: D(1), A(2), F(3)
- Stack Y: H(1), G(2), B(3)
- Stack Z: E(1), I(2), C(3)

8. Answer: Box E is in Stack Z at position 1

Verification: All 7 conditions satisfied ✓
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