Question

Why do banks keep a small portion of the deposits as cash with themselves?

Answer 1

banks keep 15 percent of there deposits as cash so as to pay those depositors who come to withdraw cash on any particular day

Answer 2

Banks keep 15 % of the total deposits made in India.
This is kept as a provision as the person who has made the deposit may withdraw his/ cash on a particular day.
Leaving this 15% of deposits rest of the cash is lent as loans.

Hope This Helps You!