Five persons S, T, U, V, and W are standing in a line facing towards the east. Only T is standing between U and S. U is standing third to the right of W and to the immediate left of V.
Who is standing at the extreme right end?

Let's find the linear arrangement from left to right (where right corresponds to moving towards the south direction if facing East, or simply treat it as standard Left-Right row layout):
"U is standing third to the right of W." This gives the relative spacing: W, _, _, U.

"U is to the immediate left of V." This means V is immediately to the right of U: W, _, _, U, V.

"Only T is standing between U and S." Since U is followed by V on the right, S must be to the left of U, with T in between them.

Filling this into our row: W, S, T, U, V.

Let's double check all conditions:

Five persons: W, S, T, U, V (Total 5).

Only T is between U and S: Yes, S, T, U.

U is third to the right of W: Positions from W are 1st (S), 2nd (T), 3rd (U). Yes.

U is to the immediate left of V: Yes.

The person standing at the extreme right end is V.