Japanese Math Problem

This is an interesting math problem that resulted from a study in Japan where they found out that now only 60% of 20~ year old students who were subjected to this question could answer it correctly. The important thing to note here is that it’s a lot lower percentage when compared to the 1980s where it was around 90%. Are we getting dumber? I don’t think so, it’s just that the importance and focus is given to other things among most kids nowadays. Also everything is just going faster and this question is actually designed to catch those impatient students who just don’t put enough time to really make sure they’re making the right assumptions.