A, B, C, D, E, F and G are travelling in a train compartment with III-tier…

In capacity-constrained arrangement puzzles, first lock the groups forced by seat capacity (a clue like “the only other person sharing X's slot-type” fixes a 2-seat group), then use direct exclusions to fill the remaining fixed-size groups, and only at the end resolve individual identities using the profession clues.

1. There are 2 lower berths, 3 middle berths and 2 upper berths (7 berths for 7 people).

2. A (the Engineer) is not on the upper berth. The Architect is described as “the only other person” occupying the same berth type as A — this phrasing fits only a 2-seat berth type, so A and the Architect must be the two lower-berth occupants.

3. B (Pathologist) and F (Lawyer) are both excluded from the middle berths. Since the two lower berths are already taken by A and the Architect, B and F must occupy the two upper berths.

4. C is a Pharmacist and has not yet been placed on a berth, so C must be one of the three middle-berth occupants.

5. The Architect cannot be B (Pathologist), C (Pharmacist) or F (Lawyer), since those professions are already assigned, and G is explicitly stated not to be the Architect. That leaves D as the Architect, confirming the lower berths hold A and D.

6. With D confirmed as the lower-berth Architect, the three middle-berth occupants are exactly the people left over: C, E and G.

7. E occupies the same berth type as the Doctor. Since E is in the middle group, the Doctor must also be in the middle group. Among the middle occupants, C is already the Pharmacist, so the Doctor is either E or G. G is stated not to be the Journalist, and the two professions still unassigned are Doctor and Journalist, so G must be the Doctor and E must be the Journalist — both consistent with sitting in the middle berths.

Final layout, checked against every clue in the puzzle:

The three people in the middle berths are C, E and G.