And NO, assuming all the lines are straight is NOT unreasonable, it is the only way that the problem could ever possibly have a solution.

Wow, you got so close to my point but still fell short! My point is that you cannot reach a solution without making assumptions that fundamentally alter the solution. Your math is correct if and only if your straight line assumption is true. It may be a reasonable assumption, but that does not mean it must always be an accurate assumption.

9 points13 hours agoIt depends on the store. There are places where the self checkout lanes are dysfunctional and end up requiring waiting for a checkout worker (who are usually understaffed) to come and scan a code to fix it.