[devy]

> the general rule that if, say, a box of nails advertises 1000 nails, the manufacturer will have set the actual average to be higher than 1000 nails so that some large majority of buyers will always have at least 1000 nails in the box.

This is actually not a good analogy. These days nails are mass produced and quality controls are good to ensure each has the same rough shape and weight +/- by a few percentage points. And to ensure a quantity for a box is actually ensuring the weight - much easier to control.

[theoh]

"Overs and unders" are still a thing in manufacturing. Up to 10% either way.

e.g. https://support.discmakers.com/hc/en-us/articles/209954927-M...

https://www.lumi.com/blog/explaining-overs-unders

http://www.admorefolders.com/overunder.html