Question

When Rafael entered the class, there were already 10 students in the class. 5 students entered the class between Roger and Rafael. Total 10 students entered after Roger. Exactly how many students are in the class finally?

• A. 15
• B. 25
• C. 27
• D. Cannot be decided

Hint:

Try both orders, Roger before Rafael and Rafael before Roger, and check if they give the same final count.

Answer 1

The Correct Option is D

A faster way to see why this question has no single fixed answer is to directly test each numeric option against the clues and check whether a consistent scenario can be built for it.

1. Test 15. Build the class as 4 students before Roger, then Roger, then 5 students entering between Roger and Rafael, then Rafael, then 4 more students after Rafael. Check the clues: when Rafael entered, students already present were 4 plus 1 for Roger plus 5 in between, which is 10, matching the clue that 10 students were already there. Students entering after Roger are 5 in between plus 1 Rafael plus 4 after Rafael, which is 10, matching the second clue exactly. This scenario works and gives a total of 4 plus 1 plus 5 plus 1 plus 4, which is 15.
2. Test 27. Build the class with Rafael entering before Roger this time. Say 10 students are present before Rafael enters, matching the clue about 10 students already there when Rafael enters. Then the 5 students who entered between Roger and Rafael enter, followed by Roger. That gives 10 plus 1 Rafael plus 5 in between plus 1 Roger, which is 17 students up to and including Roger. Then 10 more students enter after Roger, matching the clue exactly, giving a final total of 17 plus 10, which is 27.
3. Both constructions use every clue in the passage correctly and without contradiction, yet one gives 15 and the other gives 27.
4. Since two genuinely different and fully valid class sizes can be built from the same clues, options 15 and 27 cannot both be uniquely correct, and 25 does not even arise from either valid construction.
5. Because the passage never specifies whether Roger or Rafael entered the room first, this ambiguity cannot be resolved with the information given, so the only defensible answer is Cannot be decided.