Five persons are standing in a line. One of the two persons at the extreme…

Concept

Linear arrangement puzzles are solved by first fixing the anchor (who occupies the two extreme, fixed positions) and then chaining each relative-position clue - "X is to the right/left of Y", "P is standing between Q and R" - into one ordered block per convention (such clues are read as fixing immediate placement, the standard way this puzzle type is solved), merging the blocks so every clue and the anchor hold together.

Application

1. Anchor: the two extreme positions (1st and 5th, counting from the left) are held by the professor and the businessman - so the advocate, being neither, cannot stand at either extreme.

2. The clue "the student is standing between the professor and the advocate" together with "the advocate is to the right of the student" fixes the block Professor - Student - Advocate, read left to right.

3. The clue "the author is to the left of the businessman" fixes the block Author - Businessman.

4. Since the businessman cannot be the left extreme (nobody could then stand to its left for the author), the professor takes the left extreme and the businessman the right extreme.

5. Placing Professor - Student - Advocate across positions 1-3 and Author - Businessman across positions 4-5 satisfies every clue together: Professor, Student, Advocate, Author, Businessman.

Cross-check

Every clue holds against this final order: the professor and businessman are the two extreme ends; the advocate (position 3) is to the right of the student (position 2); the author (position 4) is to the left of the businessman (position 5); the student (position 2) stands between the professor (position 1) and the advocate (position 3). All four clues are satisfied, so the advocate is 3rd from the left.