Question 1
Seven boxes P, Q, R, S, T, U, and V are arranged in a vertical stack (positions 1 to 7 from bottom to top).
Box P is three positions above box Q. Box R is immediately below box S.
Box T is at the bottom. Box U is somewhere between box R and box P.
How many boxes are there between box S and box V?
Step-by-step Solution:
1. Create vertical stack (1=bottom, 7=top)
2. Direct assignments:
- Box T at bottom → Position 1 = T
3. Constraint 1: Box P is 3 positions above Box Q
- Possible pairs: (1,4), (2,5), (3,6), (4,7)
- Position 1 is T, so (1,4) invalid
- Try Q at 4, P at 7
4. Constraint 2: Box R immediately below Box S
- They occupy consecutive positions: (1,2), (2,3), (3,4), (4,5), (5,6), (6,7)
- Position 4 is Q, position 7 is P
- Try R at 2, S at 3
5. Constraint 3: Box U between R and P
- R at 2, P at 7 → positions between: 3,4,5,6
- Position 3 is S, position 4 is Q
- Place U at position 5
- Remaining box V goes to position 6
6. Final arrangement (bottom to top):
- Position 1: T
- Position 2: R
- Position 3: S
- Position 4: Q
- Position 5: U
- Position 6: V
- Position 7: P
7. Count boxes between S (pos3) and V (pos6):
- Positions between: 4 and 5 → Boxes Q and U
- Total: 2 boxes
Answer: 2 boxes
Verification:
- T at bottom ✓
- P at 7, Q at 4 → 3 positions above ✓
- R at 2, S at 3 → immediately below ✓
- U at 5 is between R(2) and P(7) ✓
- All boxes used exactly once ✓
1. Create vertical stack (1=bottom, 7=top)
2. Direct assignments:
- Box T at bottom → Position 1 = T
3. Constraint 1: Box P is 3 positions above Box Q
- Possible pairs: (1,4), (2,5), (3,6), (4,7)
- Position 1 is T, so (1,4) invalid
- Try Q at 4, P at 7
4. Constraint 2: Box R immediately below Box S
- They occupy consecutive positions: (1,2), (2,3), (3,4), (4,5), (5,6), (6,7)
- Position 4 is Q, position 7 is P
- Try R at 2, S at 3
5. Constraint 3: Box U between R and P
- R at 2, P at 7 → positions between: 3,4,5,6
- Position 3 is S, position 4 is Q
- Place U at position 5
- Remaining box V goes to position 6
6. Final arrangement (bottom to top):
- Position 1: T
- Position 2: R
- Position 3: S
- Position 4: Q
- Position 5: U
- Position 6: V
- Position 7: P
7. Count boxes between S (pos3) and V (pos6):
- Positions between: 4 and 5 → Boxes Q and U
- Total: 2 boxes
Answer: 2 boxes
Verification:
- T at bottom ✓
- P at 7, Q at 4 → 3 positions above ✓
- R at 2, S at 3 → immediately below ✓
- U at 5 is between R(2) and P(7) ✓
- All boxes used exactly once ✓