A Chemistry teacher conducts a surprise test. The students were barely prepared so they end up doing badly on the test. The teacher is angry and says, ""You students can't even write a simple test properly! 50% of you are fools!"" The next day the students look glum and when the teacher asks them why, they say, ""Sir, you had said yesterday that 50% of us are fools, that's why we aren't in a good mood today."" The teacher laughs and says, ""Haha okay then, I take back my words, 50% of you are intelligent!"" The students are now happy.