Over-Confidence !!!

On a fine day, a student who is very good at current affairs went to his school. Teacher asked the students - "Children, Do anyone know who is our Finance Minister?". He immediately raised his hand and said "Our Finance Minister is Mr. Chidambaram". Teacher said "NO" and was looking at any other answers. Unfortunately there were none. Student was confident, when the same answer was given two days back to his father, he said it is correct! All of a certain how he can change? (But poor guy doesnt know that terrorists made it possible !! ) And we all know children are generally stubborn, He once again said it is Chidambaram. Teacher said "Dont be Over Confident". Then Teacher revealed that the correct answer is "Mr. Manmohan Singh". But the student was unhappy. He was thinking "Was he really Over Confident?" And when the next day teacher asked "Who is our Petroleum Minister?". He did not responded to the question thinking that even he might have changed recently!! Thereafter he did not responded to any questions in the classroom. So what happened now? A student with some good confidence is turned out to be a student with low confidence with one word "Over Confidence". what is the meaning of Over Confidence? People say someone is confident when he is doing a good job and at last if he fails to deliver at the end, the same People call it as over confidence. When i say happening of task "X" is certain and probability of my statement becoming true is 50%. Can someone tell me whether i am confident or not? Ok atleast can someone tell me what percent the probability should be to say that "I am confident". Obviously no one can tell the exact answer. Therefore there is no demarcation between Confidence and Over Confidence. Then better we can stop using the word Over Confidence. English bashalo nachani oke oka padham "Over Confidence"