According to the given information,
Names of persons: Six person – P, Q, R, S, T and U
Working days: Monday to Saturday
Statement I: Three people went to work between U and T. U did not go to work after T. Only one person works between T and R.
Hence, we can't find the answer using statement I alone.
Statement II: Two went to work between R and S. P went to work immediately before R.
Hence, we can't find the answer using statement II alone.
By using Statement I and II both,
By using statement I and statement II together also we can't be sure who works on Thursday.
Hence,
The data in both statements I and II together is not sufficient to answer the question.