Is there any chance of getting a seat at IIM Ahmedabad if I get above 90% in the CAT exam, but I have 72% in 10th and 60% in 12th?

Honestly, there is almost no chance of getting into any IIMs with your profile with any percentile. Even getting a 99 score in CAT will not guarantee your admission into IIM Ahmedabad given your past academic score is so low.

Still, you can try your best and score the maximum CAT percentile and instead go for institutes like FMS, MDI and NITIE, IIT B/D/M. Another tip is to take XAT as it may increase your chances of admission. 

A 90-95 CAT score will open other options for you such as

• IIFT (own entrance)

• SIBM, SCMHRD (both through SNAP)

• NMIMS (through NMAT)

• IMT, XIMB, IMI, Delhi University courses (DSE, MIB, MBE)

So it’s best if you try all options and sit for various exams. Then choose the best institute for you.