Dear Student,

the age limit for the NDA entrance examination is between 16.5 to 19.5 years and the applying date is between 15.5 to 18.5 years.

So if you are coming in between the range of 15.5 to 18.5 then you will be eligible to give the NDA entrance exam of 14 nov.

As you have  choses Biology in your 12th board so you will be eligible to Join Army only and still you have to clear the maths section of NDA entrance.

And for Navy and Airforce Maths is compulsory in your 12th board subjects.

Hope this will clear all of your doubts.

good Luck :)