It is really hard to tell since in your workbook you may have ALL kinds of things from all kind of sources
It also matters how long time you have taken - 2 mins or 1.5 or 3.
The best plan/idea is to take a practice CAT (just one section if you only finished quant or verbal and see how that translates). Then you can keep a metric of right/wrong in your workbook vs. CAT.
however, it is not going to be perfect. The improvement in Workbook is good and improvement in CAT's is good but the rate of improvement will not be the same if that makes sense. The trends are good.
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