Hi Abhijeet,

I have two of my brothers who recently passed MBA from IIMs. They followed Career Launcher. One of them took study material from Career Launcher and the other just took the online test series from Career Launcher. But whichever site you follow, you have to practice yourself a lot. Emphasise on the Numerical Analysis topic in Quantitative aptitude. First of all go to Career Launcher, go through some of the previous years question paper and be thorough with the pattern of the CAT exam. For Quantitative Aptitude you can also follow  a youtube channel named Takzilla.

Hopefully this helps.