Each of P, Q, R, S, T, U and V has an exam on a different day of a week starting from Monday and ending on Sunday of the same week.
U has an exam on Thursday. Only one person has exam between P and U. T has an exam immediately after P. As many people have an exam before T as after S. Q has an exam immediately after V but not on Sunday.
How many people have an exam between R and V?
Each of P, Q, R, S, T, U and V has an exam on a different day of a week starting from Monday and ending on Sunday of the same week.
U has an exam on Thursday. Only one person has exam between P and U. T has an exam immediately after P. As many people have an exam before T as after S. Q has an exam immediately after V but not on Sunday.
How many people have an exam between R and V?
Solution
Since U has an exam on Thursday, let's work from there.
Only one person has exam between P and U:
This means P is either 2 days before or 2 days after Thursday:
- P could be on Tuesday (one person on Wednesday between them)
- P could be on Saturday (one person on Friday between them)
T has an exam immediately after P:
- If P is Tuesday → T is Wednesday
- If P is Saturday → T is Sunday
As many people have an exam before T as after S:
Testing when P = Tuesday, T = Wednesday:
- T is on day 3 → 2 people before T
- So 2 people should be after S → S is on day 5 (Friday)
Testing when P = Saturday, T = Sunday:
- T is on day 7 → 6 people before T
- So 6 people should be after S → S is on day 1 (Monday)
Q has an exam immediately after V but not on Sunday:
With P = Tuesday, T = Wednesday, U = Thursday, S = Friday:
- Remaining days: Monday, Saturday, Sunday
- V and Q must be consecutive, Q ≠ Sunday
- This is impossible with the remaining days ✗
With P = Saturday, T = Sunday, U = Thursday, S = Monday:
- Remaining days: Tuesday, Wednesday, Friday
- V and Q must be consecutive, Q ≠ Sunday
- V = Tuesday, Q = Wednesday ✓
- R = Friday (only person left)
| Day | Person |
|---|---|
| Monday | S |
| Tuesday | V |
| Wednesday | Q |
| Thursday | U |
| Friday | R |
| Saturday | P |
| Sunday | T |
Between R (Friday) and V (Tuesday), the people with exams are:
- Wednesday: Q
- Thursday: U
Two people have an exam between R and V.
Answer: Option 1