Question 1
Two parallel rows of chairs. Row 1 has D, E, C, A and B facing South.
Row 2 has T, S, Q, P and R facing North. Each person in one row faces exactly one person from the other row.
C sits fourth from the left end of Row 1. T faces C.
D sits at an extreme end of Row 1. E sits second to the right of D.
S sits second to the left of T. Q sits at an extreme end of Row 2.
R is not adjacent to T in Row 2.
Who faces E?
Solution Approach:
Step 1: Draw the double row setup
Row 1 faces South (↓), Row 2 faces North (↑)
Person at position i in Row 1 faces person at position i in Row 2.
Position: 1 2 3 4 5
Row 1 (↓): _ _ _ _ _
Row 2 (↑): _ _ _ _ _
Key direction rule:
- Row 1 (South-facing): "right" = viewer's LEFT (lower position numbers)
- Row 2 (North-facing): "right" = viewer's RIGHT (higher position numbers)
Step 2: Place Row 1 persons
- C sits 4th from the left end of Row 1 → Row 1, pos 4
- D sits at an extreme end: pos 1 or pos 5
- E sits second to the RIGHT of D (south-facing → lower position):
pos[E] = pos[D] - 2
If D at pos 1 → pos[E] = -1 (invalid ✗)
If D at pos 5 → pos[E] = 3 ✓ (pos 3 is free)
∴ D at pos 5, E at pos 3 ✓
Row 1: _ _ E C D
Remaining A,B at pos 1 and 2 (either order — pinned next).
Step 3: Place Row 2 persons
- T faces C (pos 4) → T at Row 2, pos 4
- S sits second to the LEFT of T (north-facing → lower position):
pos[S] = pos[T] - 2 = 2 → S at Row 2 pos 2 ✓
- Q sits at extreme end of Row 2: pos 1 or pos 5
- R is NOT adjacent to T (pos 4): adjacent = pos 3 and pos 5
So R ≠ pos 3 and R ≠ pos 5
Remaining positions for Q,P,R: pos 1, pos 3, pos 5
R not at pos 3 or pos 5 → R at pos 1
Q at extreme → pos 5 (since pos 1 is R) ✓
P fills pos 3 ✓
Row 2: R S P T Q
Final Arrangement:
Position: 1 2 3 4 5
Row 1 (↓): A/B A/B E C D
Row 2 (↑): R S P T Q
Find who faces E:
E is at Row 1, position 3.
Person at Row 2, position 3 = P
Answer: P faces E.
Step 1: Draw the double row setup
Row 1 faces South (↓), Row 2 faces North (↑)
Person at position i in Row 1 faces person at position i in Row 2.
Position: 1 2 3 4 5
Row 1 (↓): _ _ _ _ _
Row 2 (↑): _ _ _ _ _
Key direction rule:
- Row 1 (South-facing): "right" = viewer's LEFT (lower position numbers)
- Row 2 (North-facing): "right" = viewer's RIGHT (higher position numbers)
Step 2: Place Row 1 persons
- C sits 4th from the left end of Row 1 → Row 1, pos 4
- D sits at an extreme end: pos 1 or pos 5
- E sits second to the RIGHT of D (south-facing → lower position):
pos[E] = pos[D] - 2
If D at pos 1 → pos[E] = -1 (invalid ✗)
If D at pos 5 → pos[E] = 3 ✓ (pos 3 is free)
∴ D at pos 5, E at pos 3 ✓
Row 1: _ _ E C D
Remaining A,B at pos 1 and 2 (either order — pinned next).
Step 3: Place Row 2 persons
- T faces C (pos 4) → T at Row 2, pos 4
- S sits second to the LEFT of T (north-facing → lower position):
pos[S] = pos[T] - 2 = 2 → S at Row 2 pos 2 ✓
- Q sits at extreme end of Row 2: pos 1 or pos 5
- R is NOT adjacent to T (pos 4): adjacent = pos 3 and pos 5
So R ≠ pos 3 and R ≠ pos 5
Remaining positions for Q,P,R: pos 1, pos 3, pos 5
R not at pos 3 or pos 5 → R at pos 1
Q at extreme → pos 5 (since pos 1 is R) ✓
P fills pos 3 ✓
Row 2: R S P T Q
Final Arrangement:
Position: 1 2 3 4 5
Row 1 (↓): A/B A/B E C D
Row 2 (↑): R S P T Q
Find who faces E:
E is at Row 1, position 3.
Person at Row 2, position 3 = P
Answer: P faces E.