Hello Sachin

The marks that can be scored in a particular set of GATE depends totally on the difficulty of that set and how well you have prepared. However, the marks to be scored in GATE to get admission in IITs or IISc doesn’t necessarily depend on that. This is because of the concept of normalisation that is applied after the exam is conducted. This is done for a fair evaluation of marks for a particular student. Normalisation is done based on:

The marks you scored

The highest marks scored by a person who wrote that particular set

The average of all marks scored by everyone who wrote that particular set

Highest marks scored among all sets

Average of all marks scored among all sets

Thus, after normalisation, the marks you scored can increase or decrease, based on how everyone else performed in your set. Generally, if your set was hard, chances are your marks will increase.

Now, coming to the question, in general, you need a rank of 500 - 600 to be assured a seat in any one of the old IITs (Madras, Bombay, Delhi, Kanpur and Kharagpur) or IISc. This is a normalised mark of 74.5–76. Usually, most of the top rankers choose to go for PSUs and the rank requirement comes down. As more and more people go for PSUs, the IITs keep their spot rounds to allot more people to specializations and as a result, the rank requirements come down.

But in your case it will be hard for you get admission in any IIT bombay and madras with 500  GATE score.

Hope this will help