Six persons P, Q, R, S, T and U are sitting on a straight bench facing towards the east. Only two persons are sitting between P and Q. Only S is sitting to the left of P. Only Q is sitting between T and U. U is sitting at the end position from the right end. Who is sitting at the third position from the left end?

Let's mark the six positions on the bench from Left (1) to Right (6): "Only S is sitting to the left of P". This means S must be at the extreme left position, and P is right next to him. So, S = 1 and P = 2."Only two persons are sitting between P and Q". Since P is at position 2, Q must be at position $2+3=5$. So, Q = 5."U is sitting at the end position from the right end" $\to$ U = 6."Only Q is sitting between T and U". Since Q is at 5 and U is at 6, T must be at position 4. So, T = 4.The only remaining empty slot is position 3, which goes to the remaining person, R = 3.The full linear arrangement from left to right is:S - P - R - T - Q - UThe person sitting at the third position from the left end is R.