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Difficulty: MediumSeating Arrangement

Six astronauts—Aldrin, Collins, Glenn, Jemison, Ride, and Shepard—are seated in a single straight row facing the main presentation screen (North) during a mission briefing.

Based on the following conditions, arrange the astronauts in their correct seating order from the leftmost position to the rightmost position:

- Jemison sits third to the right of Collins.
- Ride sits at one of the extreme ends of the row.
- Aldrin sits immediately next to Ride, but is not adjacent to Jemison.
- Shepard sits to the immediate left of Glenn.

Arrange the astronauts in order from Position 1 (far left) to Position 6 (far right).

  1. 1Ride
  2. 2Aldrin
  3. 3Collins
  4. 4Shepard
  5. 5Glenn
  6. 6Jemison

Answer

The correct left-to-right order is: Ride, Aldrin, Collins, Shepard, Glenn, Jemison.
The correct sequence is derived by testing the possible ends for Ride. If Ride is at the right end (Position 6), Aldrin is at Position 5, which means Jemison cannot be at Position 4 or 6. This makes it impossible for Jemison to be third to the right of Collins. Therefore, Ride must be at the left end (Position 1), placing Aldrin at Position 2. Collins at Position 3 ensures Jemison is at Position 6. Shepard and Glenn then naturally fill Positions 4 and 5 to remain adjacent.

Step-by-Step Solution

1
Determine Ride's possible positions.
Ride is at either Position 1 (far left) or Position 6 (far right).
The conditions state that Ride sits at one of the extreme ends of the row.
2
Test placing Ride at Position 6 (far right).
This configuration is impossible and must be eliminated.
If Ride is at 6, Aldrin must be at 5. Since Jemison cannot sit next to Aldrin, Jemison cannot be at 4 or 6. This leaves no possible way for Jemison to be exactly third to the right of Collins (which would require Jemison to be at 4, 5, or 6).
3
Place Ride at Position 1 and Aldrin at Position 2.
Position 1 = Ride, Position 2 = Aldrin.
Since the right extreme is invalid, Ride must be at the left extreme. Aldrin sits immediately next to Ride.
4
Determine positions for Collins and Jemison.
Position 3 = Collins, Position 6 = Jemison.
Jemison is third to the right of Collins (pattern: Collins - empty - empty - Jemison). The only spaces that can accommodate this spread, without overlapping Aldrin at Position 2, are Positions 3 and 6.
5
Place the remaining pair, Shepard and Glenn.
Position 4 = Shepard, Position 5 = Glenn.
Shepard sits immediately to the left of Glenn. Positions 4 and 5 are the only two consecutive empty seats left in the row.

Key Concept

Logical deduction in linear arrangements by testing extreme edge cases to eliminate contradictions.
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Topics

Seating Arrangement

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