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

https://lima-wiki.win/index.php/How_Do_I_Go_from_a_Rainfall_Rate_Graph_to_Total_Rainfall%3F

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.