As a student of IIM (IIM Calcutta ,PGDM 2006), I can assure you that it is not true that the same yardstick is used to judge the students from different academic backgrounds like Arts and Engineering.If that were true, you would find no one but only IITians at IIMs. In fact, the cut offs are different for people for different streams when the calls are given, thus, an engineering student with 95 percentile in quant may not get an IIM call but a humanities student with as low as 87-88 percentile in quant may get all the calls. I would like to request people not to act on heresay coz CAT may be considered the most impartial exam in India.