Seven persons- P, Q, R, S, T, U and V go on a picnic on different days in a week starting from Monday to Sunday but not necessarily in the same order. Only one person goes on picnic each day.

U goes to the picnic on Wednesday. Only one person goes between U and T. Only three persons go between T and S. Q goes immediately before R. V goes to the picnic after P but none of them go before S.

Who goes to the picnic on Sunday?

The correct answer is Option 4: R.

Let us solve this puzzle step-by-step to find out who goes to the picnic on Sunday.

The week starts on Monday and ends on Sunday:

1. Monday
2. Tuesday
3. Wednesday
4. Thursday
5. Friday
6. Saturday
7. Sunday

Step 1: Place U in the schedule.
We are given that U goes to the picnic on Wednesday.
• Wednesday = U

Step 2: Determine the position of T.
Only one person goes between U and T. Since U is on Wednesday, T could potentially be on Monday or Friday.
• If T is on Monday, then 1 person (Tuesday) is between U and T.
• If T is on Friday, then 1 person (Thursday) is between U and T.
Let us check the next condition: "Only three persons go between T and S."
- Case A: If T is on Friday (Day 5), going 3 persons earlier puts S on Monday (Day 1). (Persons on Tue, Wed, Thu are between them).
- Case B: If T is on Monday (Day 1), going 3 persons later puts S on Friday (Day 5). (Persons on Tue, Wed, Thu are between them).

Now consider the rule: "V goes to the picnic after P but none of them go before S."
This means both P and V go after S (i.e. S must go before both P and V).
- If S were on Friday (Case B), there are only two days left (Saturday and Sunday) for P, V, Q, and R, which is impossible because Q goes immediately before R (requiring 2 consecutive days) and P & V also need days after S.
- Therefore, S must be on Monday!

So we have:
• Monday = S
• Wednesday = U
• Friday = T (3 persons between S and T: Tue, Wed, Thu)

Step 3: Place Q and R.
We are given that "Q goes immediately before R." This requires two consecutive vacant days.
Currently, the filled days are Monday (S), Wednesday (U), and Friday (T).
The available days are:
• Tuesday
• Thursday
• Saturday
• Sunday

The only consecutive pair of empty days left is Saturday and Sunday!
Thus:
• Saturday = Q
• Sunday = R

Step 4: Place P and V.
The remaining empty days are Tuesday and Thursday.
Since V goes after P:
• Tuesday = P
• Thursday = V

Final Schedule:
• Monday: S
• Tuesday: P
• Wednesday: U
• Thursday: V
• Friday: T
• Saturday: Q
• Sunday: R

Therefore, R goes to the picnic on Sunday.