Weight Comparison Ordering

6 positions from heaviest (1) to lightest (6): S is lighter than only Q $\implies$ Q is 1st, S is 2nd. P is heavier than 3 persons $\implies$ P is 3rd. Remaining 4th, 5th, 6th positions for T, R, U. R is lighter than T and R is not the lightest $\implies$ T is 4th, R is 5th, U is 6th. Order: Q > S > P > T > R > U. Lighter than P is T; heavier than P is S. So T and S respectively.