Teaser-economics problem. Love it.
first observation: You will be last in line, no matter which line you chose. It only matters which line when another person comes after you.
second observation: what do the people in the longer line know that you don't know? The last person in the longer line must know that being in the second line, although longer, must be faster than the shorter line.
third observation: No one really cares what line you chose because you are the tail end charlie. The other people have already made their choice. It is only you, who has the decision.
For my time: I'd chose the longer line and ask the previous last guy, "why is the other line so short?"
first observation: You will be last in line, no matter which line you chose. It only matters which line when another person comes after you.
second observation: what do the people in the longer line know that you don't know? The last person in the longer line must know that being in the second line, although longer, must be faster than the shorter line.
third observation: No one really cares what line you chose because you are the tail end charlie. The other people have already made their choice. It is only you, who has the decision.
For my time: I'd chose the longer line and ask the previous last guy, "why is the other line so short?"