i see some time per question in reading section for example that are as less as 1 second. How is that possible?
How do Uworld calculate these number? are they the average or the best of ?

The reported time per question is pulled from average user performance on that question. Because we're always updating our QBank with new and revised questions, you'll occasionally encounter questions that very few other students have taken, and some of them may have skipped the question.

So, when you encounter a very low time per question, you're likely one of the first to see that version of the question. In those cases, we do not recommend measuring yourself against the average user performance.