Learn how a running total of parcels delivered differs from a rate in parcels...

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

Learn how a running total of parcels delivered differs from a rate in parcels per hour. With clear time windows, this article shows when to ask “how many so far?” and when to ask “how fast?”—so a shift chart is easier to read without mixing units.