This is one of the most interesting and useful pieces of information we have heard in a long time. "When choosing which line will be the fastest at the grocery store, it might surprise you to learn that the "express" lane may not always be the best choice. The number of people in line adds more to the wait time than the number of items each person has in their cart!" A math teacher named Dan Meyer came up with this theory.
""When you add one person to the line, you're adding 48 extra seconds to the line length (that's "tender time" added to "other time") without even considering the items in her cart. Meanwhile, an extra item only costs you an extra 2.8 seconds. Therefore, you'd rather add 17 more items to the line than one extra person!"" http://lifehacker.com/5369876/how-to-choose-the-fastest-line-at-the-market?skyline=true&s=i