Indian Statistical Institute conducts offline ISI admission test every year for admissions.
For admission to B.Sc Statistics you should be eligible that is you should have successfully passed 10+2 examinations with Mathematics and English as compulsory subjects.
You have to score good in ISI admission tests to get selected for personal interview (ISI releases a Cut-Off for selection in Interview), on the basis of performance in Interview session final list of students is prepared.
You can apply online or offline in ISI admission test 2020 on the official website, As application date was in February and March.
But INMO awardees are directly called for the interview session (they also have no requirement to give ISI admission test).