Learn how a running total differs from a rate of change with parcel deliveries....

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

Learn how a running total differs from a rate of change with parcel deliveries. Forty-eight parcels by noon is a total; 12 parcels per hour is a rate over a specific time window. The article explains how units and timing help you read both correctly.