Box/Stack Puzzles - Beginner Level: stack positions BEGINNER

Level up your box/stack puzzles skills with this entry level practice. 20 beginner-level problems await in Worksheet 4 of 30. Focus area: stack positions. Learn stack positions, box order, stacking logic through systematic practice. Designed for entry-level learners seeking foundational concepts and basic patterns.

📝 Worksheet 4 of 30 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Beginner level

What you'll learn in this worksheet:
Your progress through Box/Stack Puzzles
Worksheet 4 of 30 (13% complete)

Question 1

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 2

Six boxes A, B, C, D, E, F are stacked vertically (positions 1-6, bottom to top). Each box has a different color: Red, Blue, Green, Yellow, White, and Pink. Given conditions: - Box A is Red and at position 4 - The Blue box is immediately above the Green box - Box B is Yellow and at the bottom (position 1) - Box C is at position 5 - The White box is at position 5 - The Pink box is at the top (position 6) - Box D is Blue What is the color of box C?
Step-by-step Solution:

1. Direct assignments from conditions:
- Position 1 = Box B (Yellow) [bottom]
- Position 4 = Box A (Red)
- Position 5 = Box C (also White box)
- Position 6 = Pink box

2. Blue immediately above Green:
- Possible consecutive pairs: (1,2), (2,3), (3,4), (4,5), (5,6)
- Position 4 is Red, position 5 is White, position 6 is Pink
- Position 1 is Yellow (B)
- Therefore, Green and Blue must be at positions 2 and 3
- Green at 2, Blue at 3 (Blue above Green) ✓

3. Box D is Blue:
- Blue at position 3 → Box D at position 3

4. Remaining box E:
- All positions filled: 1(B), 2(E/Green), 3(D/Blue), 4(A/Red), 5(C/White), 6(F/Pink)
- Therefore, box E must be at position 2 (Green)

5. Final stack (bottom to top):
- Position 1: B (Yellow)
- Position 2: E (Green)
- Position 3: D (Blue)
- Position 4: A (Red)
- Position 5: C (White)
- Position 6: F (Pink)

6. Answer: Box C is White

Verification of all conditions:
- A at position 4, Red ✓
- Blue (pos3) immediately above Green (pos2) ✓
- B at bottom, Yellow ✓
- C at position 5 ✓
- White box at position 5 ✓
- Pink at top ✓
- D is Blue ✓
- All colors unique ✓
- All positions filled ✓

Question 3

Six boxes P, Q, R, S, T, and U are in a vertical stack (positions 1-6, bottom to top). Given conditions: - If P is above Q, then R is at an even position - S is exactly in the middle of the stack - U is not adjacent to S - T is at the bottom - P is two positions above Q Based on these conditions, which box can NEVER be at the top (position 6)?
Step-by-step Solution:

1. Fixed positions from given conditions:
- T is at bottom → Position 1 = T
- S is exactly in the middle → For 6 boxes, middle positions are 3 or 4
- P is two positions above Q → P's position = Q's position + 2

2. Determine valid arrangement:
- Since P = Q + 2, possible pairs: (1,3), (2,4), (3,5), (4,6)
- Position 1 is T, so (1,3) invalid
- Try Q=2, P=4:
* Then S can be at position 3 (middle)
* R must be at even position (2,4,6) but 2 and 4 taken → R=6
* U must not be adjacent to S (pos3) → cannot be at 2 or 4 → U=5
* All positions filled: 1=T, 2=Q, 3=S, 4=P, 5=U, 6=R ✓

3. Test if each box can be at top (position 6):
- T: Fixed at bottom → Cannot be at top ❌
- Q: If Q at 6, then P would be at 8 (invalid) → Cannot be at top ❌
- P: Can be at top if Q=4, P=6 (with S=3, R=2, U=5) → Possible ✓
- R: Can be at top as shown in our arrangement → Possible ✓
- S: Can be at top if S=6 (but then middle would be 3, possible with adjustments) → Possible ✓
- U: Can be at top with different arrangement → Possible ✓

4. Only Q and T cannot be at top:
- T is explicitly fixed at bottom
- Q is mathematically impossible at top due to P=Q+2 constraint

5. The question asks "which box" (singular):
- Since T is explicitly stated to be at bottom, it's obvious
- Q is the non-obvious answer that requires deduction
- Therefore, Q is the intended answer

Answer: Box Q can never be at the top

Verification:
- In any valid arrangement, Q's maximum position is 4 (when P=6)
- Q at position 6 would require P at 8 (outside stack)
- Therefore Q is impossible at top ✓

Question 4

Six boxes P, Q, R, S, T, and U are in a vertical stack (positions 1-6, bottom to top). Given conditions: - If P is above Q, then R is at an even position - S is exactly in the middle of the stack - U is not adjacent to S - T is at the bottom - P is two positions above Q Based on these conditions, which box can NEVER be at the top (position 6)?
Step-by-step Solution:

1. Fixed positions from given conditions:
- T is at bottom → Position 1 = T
- S is exactly in the middle → For 6 boxes, middle positions are 3 or 4
- P is two positions above Q → P's position = Q's position + 2

2. Determine valid arrangement:
- Since P = Q + 2, possible pairs: (1,3), (2,4), (3,5), (4,6)
- Position 1 is T, so (1,3) invalid
- Try Q=2, P=4:
* Then S can be at position 3 (middle)
* R must be at even position (2,4,6) but 2 and 4 taken → R=6
* U must not be adjacent to S (pos3) → cannot be at 2 or 4 → U=5
* All positions filled: 1=T, 2=Q, 3=S, 4=P, 5=U, 6=R ✓

3. Test if each box can be at top (position 6):
- T: Fixed at bottom → Cannot be at top ❌
- Q: If Q at 6, then P would be at 8 (invalid) → Cannot be at top ❌
- P: Can be at top if Q=4, P=6 (with S=3, R=2, U=5) → Possible ✓
- R: Can be at top as shown in our arrangement → Possible ✓
- S: Can be at top if S=6 (but then middle would be 3, possible with adjustments) → Possible ✓
- U: Can be at top with different arrangement → Possible ✓

4. Only Q and T cannot be at top:
- T is explicitly fixed at bottom
- Q is mathematically impossible at top due to P=Q+2 constraint

5. The question asks "which box" (singular):
- Since T is explicitly stated to be at bottom, it's obvious
- Q is the non-obvious answer that requires deduction
- Therefore, Q is the intended answer

Answer: Box Q can never be at the top

Verification:
- In any valid arrangement, Q's maximum position is 4 (when P=6)
- Q at position 6 would require P at 8 (outside stack)
- Therefore Q is impossible at top ✓

Question 5

Five boxes A, B, C, D, and E are stacked vertically (positions 1-5, bottom to top). Their weights follow certain rules: - The heaviest box is at the bottom - Box A is heavier than box B but lighter than box C - Box D is the lightest - Box E is heavier than A but lighter than C - Box B is heavier than D Which box is at position 3?
Step-by-step Solution:

1. Establish weight relationships:
- A > B and C > A → So C > A > B
- D is lightest → D is smallest
- E > A and C > E → So C > E > A
- B > D

2. Combine all inequalities:
- From C > E > A and A > B, we get: C > E > A > B
- And B > D, so: C > E > A > B > D

3. Complete weight order (heaviest to lightest):
C > E > A > B > D

4. Stacking rule: Heaviest at bottom (position 1), lightest at top (position 5)
- Position 1 (bottom): C (heaviest)
- Position 2: E
- Position 3: A
- Position 4: B
- Position 5 (top): D (lightest)

5. Answer: Box A is at position 3

Verification:
- Heaviest (C) at bottom ✓
- A heavier than B (pos3 vs pos4) ✓
- A lighter than C (pos3 vs pos1) ✓
- D lightest at top ✓
- E heavier than A (pos2 vs pos3) ✓
- E lighter than C (pos2 vs pos1) ✓
- B heavier than D (pos4 vs pos5) ✓

Question 6

Six family members - Grandfather (G), Father (F), Uncle (U), Son (S), Nephew (N), and Grandson (GS) - have their boxes arranged in two vertical stacks (Stack A and Stack B), with 3 boxes in each stack. Positions are numbered 1 to 3 from bottom to top in each stack. Family relationships (generations from oldest to youngest): - Generation 1 (oldest): Grandfather (G) - Generation 2: Father (F), Uncle (U) - Generation 3: Son (S), Nephew (N) - Generation 4 (youngest): Grandson (GS) Conditions: - No two boxes from the same generation are in the same stack - The oldest generation member is at the bottom of Stack A - Father's box is in Stack B - Son's box is immediately above his son's (Grandson's) box Which box is at the top of Stack A?
Step-by-step Solution:

1. Understand generations:
- Gen 1 (oldest): G
- Gen 2: F, U
- Gen 3: S, N
- Gen 4 (youngest): GS

2. Apply "oldest at bottom of Stack A":
- Stack A, position 1 = G

3. Apply "Father (F) in Stack B":
- F is in Stack B (position TBD)

4. Apply "Son (S) immediately above Grandson (GS)":
- They must be in same stack with S directly above GS
- Possible positions: (GS at 1, S at 2) or (GS at 2, S at 3)
- They cannot be in Stack A because G is at position 1
- So they must be in Stack B
- Place GS at position 1, S at position 2 in Stack B

5. Stack B so far:
- Position 1: GS (gen4)
- Position 2: S (gen3)
- Position 3: F (gen2) - must go here

6. Remaining boxes for Stack A:
- Used: G (Stack A), F, S, GS (Stack B)
- Remaining: U (gen2) and N (gen3)

7. Fill Stack A:
- Position 1: G (gen1)
- Position 2: N (gen3) - can't put U (gen2) adjacent to same gen? No same gen restriction applies to same stack
- Position 3: U (gen2)

8. Verify no same generation in same stack:
- Stack A: gen1 (G), gen3 (N), gen2 (U) → all different ✓
- Stack B: gen4 (GS), gen3 (S), gen2 (F) → all different ✓

9. Final arrangements:
- Stack A (bottom to top): G, N, U
- Stack B (bottom to top): GS, S, F

10. Answer: Box U (Uncle) is at the top of Stack A

Verification: All conditions satisfied ✓

Question 7

Six family members - Grandfather (G), Father (F), Uncle (U), Son (S), Nephew (N), and Grandson (GS) - have their boxes arranged in two vertical stacks (Stack A and Stack B), with 3 boxes in each stack. Positions are numbered 1 to 3 from bottom to top in each stack. Family relationships (generations from oldest to youngest): - Generation 1 (oldest): Grandfather (G) - Generation 2: Father (F), Uncle (U) - Generation 3: Son (S), Nephew (N) - Generation 4 (youngest): Grandson (GS) Conditions: - No two boxes from the same generation are in the same stack - The oldest generation member is at the bottom of Stack A - Father's box is in Stack B - Son's box is immediately above his son's (Grandson's) box Which box is at the top of Stack A?
Step-by-step Solution:

1. Understand generations:
- Gen 1 (oldest): G
- Gen 2: F, U
- Gen 3: S, N
- Gen 4 (youngest): GS

2. Apply "oldest at bottom of Stack A":
- Stack A, position 1 = G

3. Apply "Father (F) in Stack B":
- F is in Stack B (position TBD)

4. Apply "Son (S) immediately above Grandson (GS)":
- They must be in same stack with S directly above GS
- Possible positions: (GS at 1, S at 2) or (GS at 2, S at 3)
- They cannot be in Stack A because G is at position 1
- So they must be in Stack B
- Place GS at position 1, S at position 2 in Stack B

5. Stack B so far:
- Position 1: GS (gen4)
- Position 2: S (gen3)
- Position 3: F (gen2) - must go here

6. Remaining boxes for Stack A:
- Used: G (Stack A), F, S, GS (Stack B)
- Remaining: U (gen2) and N (gen3)

7. Fill Stack A:
- Position 1: G (gen1)
- Position 2: N (gen3) - can't put U (gen2) adjacent to same gen? No same gen restriction applies to same stack
- Position 3: U (gen2)

8. Verify no same generation in same stack:
- Stack A: gen1 (G), gen3 (N), gen2 (U) → all different ✓
- Stack B: gen4 (GS), gen3 (S), gen2 (F) → all different ✓

9. Final arrangements:
- Stack A (bottom to top): G, N, U
- Stack B (bottom to top): GS, S, F

10. Answer: Box U (Uncle) is at the top of Stack A

Verification: All conditions satisfied ✓

Question 8

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 9

Six family members - Grandfather (G), Father (F), Uncle (U), Son (S), Nephew (N), and Grandson (GS) - have their boxes arranged in two vertical stacks (Stack A and Stack B), with 3 boxes in each stack. Positions are numbered 1 to 3 from bottom to top in each stack. Family relationships (generations from oldest to youngest): - Generation 1 (oldest): Grandfather (G) - Generation 2: Father (F), Uncle (U) - Generation 3: Son (S), Nephew (N) - Generation 4 (youngest): Grandson (GS) Conditions: - No two boxes from the same generation are in the same stack - The oldest generation member is at the bottom of Stack A - Father's box is in Stack B - Son's box is immediately above his son's (Grandson's) box Which box is at the top of Stack A?
Step-by-step Solution:

1. Understand generations:
- Gen 1 (oldest): G
- Gen 2: F, U
- Gen 3: S, N
- Gen 4 (youngest): GS

2. Apply "oldest at bottom of Stack A":
- Stack A, position 1 = G

3. Apply "Father (F) in Stack B":
- F is in Stack B (position TBD)

4. Apply "Son (S) immediately above Grandson (GS)":
- They must be in same stack with S directly above GS
- Possible positions: (GS at 1, S at 2) or (GS at 2, S at 3)
- They cannot be in Stack A because G is at position 1
- So they must be in Stack B
- Place GS at position 1, S at position 2 in Stack B

5. Stack B so far:
- Position 1: GS (gen4)
- Position 2: S (gen3)
- Position 3: F (gen2) - must go here

6. Remaining boxes for Stack A:
- Used: G (Stack A), F, S, GS (Stack B)
- Remaining: U (gen2) and N (gen3)

7. Fill Stack A:
- Position 1: G (gen1)
- Position 2: N (gen3) - can't put U (gen2) adjacent to same gen? No same gen restriction applies to same stack
- Position 3: U (gen2)

8. Verify no same generation in same stack:
- Stack A: gen1 (G), gen3 (N), gen2 (U) → all different ✓
- Stack B: gen4 (GS), gen3 (S), gen2 (F) → all different ✓

9. Final arrangements:
- Stack A (bottom to top): G, N, U
- Stack B (bottom to top): GS, S, F

10. Answer: Box U (Uncle) is at the top of Stack A

Verification: All conditions satisfied ✓

Question 10

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 11

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 12

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 13

Six family members - Grandfather (G), Father (F), Uncle (U), Son (S), Nephew (N), and Grandson (GS) - have their boxes arranged in two vertical stacks (Stack A and Stack B), with 3 boxes in each stack. Positions are numbered 1 to 3 from bottom to top in each stack. Family relationships (generations from oldest to youngest): - Generation 1 (oldest): Grandfather (G) - Generation 2: Father (F), Uncle (U) - Generation 3: Son (S), Nephew (N) - Generation 4 (youngest): Grandson (GS) Conditions: - No two boxes from the same generation are in the same stack - The oldest generation member is at the bottom of Stack A - Father's box is in Stack B - Son's box is immediately above his son's (Grandson's) box Which box is at the top of Stack A?
Step-by-step Solution:

1. Understand generations:
- Gen 1 (oldest): G
- Gen 2: F, U
- Gen 3: S, N
- Gen 4 (youngest): GS

2. Apply "oldest at bottom of Stack A":
- Stack A, position 1 = G

3. Apply "Father (F) in Stack B":
- F is in Stack B (position TBD)

4. Apply "Son (S) immediately above Grandson (GS)":
- They must be in same stack with S directly above GS
- Possible positions: (GS at 1, S at 2) or (GS at 2, S at 3)
- They cannot be in Stack A because G is at position 1
- So they must be in Stack B
- Place GS at position 1, S at position 2 in Stack B

5. Stack B so far:
- Position 1: GS (gen4)
- Position 2: S (gen3)
- Position 3: F (gen2) - must go here

6. Remaining boxes for Stack A:
- Used: G (Stack A), F, S, GS (Stack B)
- Remaining: U (gen2) and N (gen3)

7. Fill Stack A:
- Position 1: G (gen1)
- Position 2: N (gen3) - can't put U (gen2) adjacent to same gen? No same gen restriction applies to same stack
- Position 3: U (gen2)

8. Verify no same generation in same stack:
- Stack A: gen1 (G), gen3 (N), gen2 (U) → all different ✓
- Stack B: gen4 (GS), gen3 (S), gen2 (F) → all different ✓

9. Final arrangements:
- Stack A (bottom to top): G, N, U
- Stack B (bottom to top): GS, S, F

10. Answer: Box U (Uncle) is at the top of Stack A

Verification: All conditions satisfied ✓

Question 14

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 15

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 16

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 17

Six boxes A, B, C, D, E, F are stacked vertically (positions 1-6, bottom to top). Each box has a different color: Red, Blue, Green, Yellow, White, and Pink. Given conditions: - Box A is Red and at position 4 - The Blue box is immediately above the Green box - Box B is Yellow and at the bottom (position 1) - Box C is at position 5 - The White box is at position 5 - The Pink box is at the top (position 6) - Box D is Blue What is the color of box C?
Step-by-step Solution:

1. Direct assignments from conditions:
- Position 1 = Box B (Yellow) [bottom]
- Position 4 = Box A (Red)
- Position 5 = Box C (also White box)
- Position 6 = Pink box

2. Blue immediately above Green:
- Possible consecutive pairs: (1,2), (2,3), (3,4), (4,5), (5,6)
- Position 4 is Red, position 5 is White, position 6 is Pink
- Position 1 is Yellow (B)
- Therefore, Green and Blue must be at positions 2 and 3
- Green at 2, Blue at 3 (Blue above Green) ✓

3. Box D is Blue:
- Blue at position 3 → Box D at position 3

4. Remaining box E:
- All positions filled: 1(B), 2(E/Green), 3(D/Blue), 4(A/Red), 5(C/White), 6(F/Pink)
- Therefore, box E must be at position 2 (Green)

5. Final stack (bottom to top):
- Position 1: B (Yellow)
- Position 2: E (Green)
- Position 3: D (Blue)
- Position 4: A (Red)
- Position 5: C (White)
- Position 6: F (Pink)

6. Answer: Box C is White

Verification of all conditions:
- A at position 4, Red ✓
- Blue (pos3) immediately above Green (pos2) ✓
- B at bottom, Yellow ✓
- C at position 5 ✓
- White box at position 5 ✓
- Pink at top ✓
- D is Blue ✓
- All colors unique ✓
- All positions filled ✓

Question 18

Six boxes A, B, C, D, E, F are stacked vertically (positions 1-6, bottom to top). Each box has a different color: Red, Blue, Green, Yellow, White, and Pink. Given conditions: - Box A is Red and at position 4 - The Blue box is immediately above the Green box - Box B is Yellow and at the bottom (position 1) - Box C is at position 5 - The White box is at position 5 - The Pink box is at the top (position 6) - Box D is Blue What is the color of box C?
Step-by-step Solution:

1. Direct assignments from conditions:
- Position 1 = Box B (Yellow) [bottom]
- Position 4 = Box A (Red)
- Position 5 = Box C (also White box)
- Position 6 = Pink box

2. Blue immediately above Green:
- Possible consecutive pairs: (1,2), (2,3), (3,4), (4,5), (5,6)
- Position 4 is Red, position 5 is White, position 6 is Pink
- Position 1 is Yellow (B)
- Therefore, Green and Blue must be at positions 2 and 3
- Green at 2, Blue at 3 (Blue above Green) ✓

3. Box D is Blue:
- Blue at position 3 → Box D at position 3

4. Remaining box E:
- All positions filled: 1(B), 2(E/Green), 3(D/Blue), 4(A/Red), 5(C/White), 6(F/Pink)
- Therefore, box E must be at position 2 (Green)

5. Final stack (bottom to top):
- Position 1: B (Yellow)
- Position 2: E (Green)
- Position 3: D (Blue)
- Position 4: A (Red)
- Position 5: C (White)
- Position 6: F (Pink)

6. Answer: Box C is White

Verification of all conditions:
- A at position 4, Red ✓
- Blue (pos3) immediately above Green (pos2) ✓
- B at bottom, Yellow ✓
- C at position 5 ✓
- White box at position 5 ✓
- Pink at top ✓
- D is Blue ✓
- All colors unique ✓
- All positions filled ✓

Question 19

Six family members - Grandfather (G), Father (F), Uncle (U), Son (S), Nephew (N), and Grandson (GS) - have their boxes arranged in two vertical stacks (Stack A and Stack B), with 3 boxes in each stack. Positions are numbered 1 to 3 from bottom to top in each stack. Family relationships (generations from oldest to youngest): - Generation 1 (oldest): Grandfather (G) - Generation 2: Father (F), Uncle (U) - Generation 3: Son (S), Nephew (N) - Generation 4 (youngest): Grandson (GS) Conditions: - No two boxes from the same generation are in the same stack - The oldest generation member is at the bottom of Stack A - Father's box is in Stack B - Son's box is immediately above his son's (Grandson's) box Which box is at the top of Stack A?
Step-by-step Solution:

1. Understand generations:
- Gen 1 (oldest): G
- Gen 2: F, U
- Gen 3: S, N
- Gen 4 (youngest): GS

2. Apply "oldest at bottom of Stack A":
- Stack A, position 1 = G

3. Apply "Father (F) in Stack B":
- F is in Stack B (position TBD)

4. Apply "Son (S) immediately above Grandson (GS)":
- They must be in same stack with S directly above GS
- Possible positions: (GS at 1, S at 2) or (GS at 2, S at 3)
- They cannot be in Stack A because G is at position 1
- So they must be in Stack B
- Place GS at position 1, S at position 2 in Stack B

5. Stack B so far:
- Position 1: GS (gen4)
- Position 2: S (gen3)
- Position 3: F (gen2) - must go here

6. Remaining boxes for Stack A:
- Used: G (Stack A), F, S, GS (Stack B)
- Remaining: U (gen2) and N (gen3)

7. Fill Stack A:
- Position 1: G (gen1)
- Position 2: N (gen3) - can't put U (gen2) adjacent to same gen? No same gen restriction applies to same stack
- Position 3: U (gen2)

8. Verify no same generation in same stack:
- Stack A: gen1 (G), gen3 (N), gen2 (U) → all different ✓
- Stack B: gen4 (GS), gen3 (S), gen2 (F) → all different ✓

9. Final arrangements:
- Stack A (bottom to top): G, N, U
- Stack B (bottom to top): GS, S, F

10. Answer: Box U (Uncle) is at the top of Stack A

Verification: All conditions satisfied ✓

Question 20

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
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