Hi dadagreat,

None of the questions in the Challenge Problem Archive overlap with our Question Banks. Furthermore, both of these sets of questions do not overlap with those we provide to students in our CAT Exams - each question pool is mutually exclusive.

Personally, I feel that the Question Banks are more useful simply because they cover both quant and verbal questions. Additionally, the Challenge Problem Archive contains some ridiculously difficult questions that are geared towards students who are already scoring very high in the quant section. The Question Banks contain questions that are less challenging overall, but cover more topics.

Hope this helps!

Best,