Learn how running totals differ from rates of change through parcel deliveries....

https://activecalculus.org/author/Running-Totals-Rates-of-Change

Learn how running totals differ from rates of change through parcel deliveries. “120 parcels by noon” is a total, while “15 parcels per hour from 10 to 11” is a rate. See how units and time windows clarify what each number means.