.
100 candidates for 1st position;
99 candidates for 2nd position (the remaining students in the class);
98 candidates for 3rd position (the remaining students in the class).
In total, there are 100*99*98 = 970200 distinct ways. ANSWER
Solved in full, with comprehensive explanations.
-------------------
To see many other similar and different problems solved with complete explanations, look into the lesson
- Special type permutations problems
in this site.
Learn the subject from there once and for all.
The standard mantra is the same for all such problems.
These problems relate to permutations, where the order in selected subsets (triples, in this case) DOES MATTER.