Thanks, they reviewed and interviewed top 75% applicants and rank them from 1-110. So rank 96th is in the range of 100 max that they can offer. Is there anything i can do to convince the Dean to take 1 more or all 100 as usual?
The time to convince anyone was during your interview.
Clearly, you did not come across as someone who would thrive in the program. Perhaps there was a significant gap between the impression your application made and that of the person who ranked 95.
They may have room for 100 students, but they also have a reputation to maintain.
Now, if they accepted applicants 97 - 100 into the program, then you have an argument.
However, usually the dean is not the one who made the application decision - that is usually done by a separate committee. While you can ask the dean, the dean is unlikely to appeal the committee decision just based on your talking to him. You could ask if there is a process in place at the institution whereby you can appeal such decisions.
OR you could take some related courses this year and apply next year. For example, I knew someone who got rejected for vet. school and just kept reapplying while doing graduate work in animal nutrition - when that person finally got a DVM, the masters in animal nutrition helped in getting a research job.