Hii aspirant ,

Coming to your question I would like to tell you that yes it is necessary to study  physics as a compulsory subject in the ISI B maths course , as you are going to be study this subject in your 2 nd sem of your degree for more information you can go to the link stated below,

www.isical.ac.in › ~deanweb › BM...

Web results

INDIAN STATISTICAL INSTITUTE B. MATH.(HONS.) PROGRAMME 1

Hope this helps you ,

Good luck.