If you start preparing for CAT and do it sincerely everyday for a year you can easily crack CAT. Learn the concepts by heart and take mock tests on each of the three sections and 2-3 mock tests as a whole you are good to go. The cutoff percentile(Minimum criteria) for the top 10 IIMs as of 2020 are:

1. IIM Ahmedabad - 80
2. IIM Bangalore - 85
3. IIM Calcutta - 85
4. IIM Lucknow - 90
5. IIM Indore - 90
6. IIM Kozhikode - 90
7. IIM Tiruchirapalli - 95

Hope it hepled.

1. IIM Shillong - 90
2. IIM Udaipur - 95
3. IIM Rohtak - 95