Dear student,
According to 2011 census the percentage of Singhalese was approx. 75% and Sri lankan Tamils was 11/15%.Sinhalese reside in the South, Central, Sabaragamuwa and Western parts of the country whereas Sri Lnakn tamils reside in the Northern areas and are the largest ethnic group in the eastern area.Sighalese are buddhisht mainlt Therawadi sect whereas Sri Lankan Tamils are the followers of Shiva.
Regards,