Bank interest on a minimum monthly balance

During one month, a school savings account had a starting balance of $3,758.40, a minimum balance of $3,702.80, and an ending balance of $3,758.80

This fictional account uses a minimum-monthly-balance rule: interest is 2.5% per month on that minimum. This is a monthly, not annual, rate. All stated balances are before the month-end interest and listed fees; both are applied afterwards. Other accounts may use different rules

The monthly fee is a service fee of $0.85