An easy, but amusing "spot the outlier" problem. The US postal service has for nearly a decade offered a very popular
flat-rate shipping option for priority (and other kinds) of mail. I use the FR boxes - mostly the medium, occasionally the large - all the time. Recently I had a smaller set of items to ship, so I looked into the small flat-rate box, which costs slightly less than half the medium-box rate. I figured the volume ratio of those 2 boxes should thus be roughly proportional to the cost ratio, which should allow my items, needing roughly one-third the volume of a medium-sized box, to fit into a small box. Not even close. Hence the resulting puzzle problem.
Using domestic priority mail and the in-store costs in the above-linked table, compute the shipping cost per cubic foot (use the internal box dimensions) of the 4 flat-rate boxes: small, 2 types of medium, large. Based on cost-per-volume, which is the best value? Which deserves the appellation "blatant rip-off"?