Each of C, D, I, J, Q, P and X has an exam on a different day of a week…
2025
Each of C, D, I, J, Q, P and X has an exam on a different day of a week starting from Monday and ending on Sunday of the same week. Only I has an exam before P. X has an exam immediately after P. No one has an exam after Q. C has an exam on one of the days after D and on one of the days before J.
How many people have exams between D and J?
- A.
Three
- B.
Four
- C.
Two
- D.
One
Show answer & explanation
Correct answer: D
Concept:
In a linear scheduling puzzle the positions are filled in order of certainty, not in the order the clues are written. A clue that counts how many people fall before or after someone is an absolute anchor, because it pins that person to one exact position. A clue saying that one person comes immediately after another only fixes a block of consecutive positions, and a chain saying that one person is earlier than a second who is in turn earlier than a third fixes relative order alone, so it is placed last, into whatever positions are still free.
Application:
There are seven people and seven days, one exam each, so Monday to Sunday are all occupied exactly once and no day is empty.
"No one has an exam after Q" is an absolute anchor at the far end: Q takes the last day, Sunday.
"Only I has an exam before P" is an absolute anchor at the near end: exactly one exam is scheduled earlier than P’s, and that exam is I’s. So I takes Monday and P takes Tuesday.
"X has an exam immediately after P" places X on the day right after Tuesday, so X takes Wednesday.
Thursday, Friday and Saturday are the only days still free, and they must hold D, C and J with D earlier than C and C earlier than J. So D takes Thursday, C takes Friday and J takes Saturday.
Day | Person |
|---|---|
Monday | I |
Tuesday | P |
Wednesday | X |
Thursday | D |
Friday | C |
Saturday | J |
Sunday | Q |
Cross-check:
Only I before P: Monday is the single day earlier than Tuesday, and it holds I.
X immediately after P: Tuesday is followed by Wednesday, which holds X.
No one after Q: Sunday is the final day of the week, and it holds Q.
D before C before J: Thursday, then Friday, then Saturday.
D sits on Thursday and J sits on Saturday, so the only day in the gap is Friday, which holds C. Exactly one person, C, has an exam between D and J.
A useful structural point: I, P and X occupy three consecutive days, and the days strictly between D and J are bounded by D’s own day and J’s own day. The trio therefore cannot be split across that boundary — it lies either wholly inside the D-to-J gap or wholly outside it. Here it lies entirely before D, which is why the gap contains C alone.