See how a running total differs from a rate of change through parcels and rain....

https://atomic-wiki.win/index.php/What_should_I_write_before_doing_any_arithmetic_with_a_real-world_dataset%3F

See how a running total differs from a rate of change through parcels and rain. Learn to check units and time windows: packages delivered so far is a count, while inches of rain per hour is a rate