Prelim
The prelim paper can be located here. It is available both as a postscript file ready for printing as well as a html file for your viewing pleasure. Here are the answers in ps and html formats. The paper was for a total of 100 points. Scoring was distinctly binary, either you got the marks or you didn't. Average scores were in the 17-20 range. Very very depressing. The highest score was 40 from Sharat from KREC, Surathkal.
Finals
The top 7 teams from the prelims qualified for the finals. The minimum qualifying score was 24/100. The paper which was used in finals is here as well (ps , html ). Answers should be up soon. :)). The finals was won by Sharat from KREC, Surathkal with Bipin and Arun from RVCE coming in second. Irfan from KREC Surathkal came in third.
Some Nice Answers
When I set the last question in the prelims paper, I certainly expected to see some interesting answers, but my expectations were seriously exceeded. Here are the best of the best. The question read:
Q. I bring you three inverted cups and tell you there is gold under one of them. You pick one, but before you open, I open one of the other cups and show you that it is actually empty. Would you like to switch the choice you made before?
The official version is contained in the answers if you want to try it right now. Here are some of the answers that I got, raw, unedited and real life:
- I won't want to switch as it's more efficient in terms of time to hold on to my cup.
- No, I won't switch as we should believe in ourselves.
- No. Because before I open the cup you have already opened the cup. When you opened the cup there is two possibilities:
1. Gold coin present
2. Gold coin not present
So, I come to know that cap has gold coin or now. SoAlso you have opened I also open the other cup. So there is two possibilities in my case:
1. Gold coin present in my cup
2. Gold coin not present in my cup
So I come to know whether the third cup has gold or not. So I need not switch.
- I would not go for another cup, or I won't switch.
In this particular situation the intention of yours is very important. Since, you bring the inverted cups, you know where the gold is. Your intention is that I should not be in a position to find a cup which has gold.
So, when I go for the right one, you are just trying to distract my concentration. So, I ll go for the one which I have selected first.
- I wouldn't switch. I stand a 50-50 chance of getting gold with 2 cups. I would rather try and if I'm lucky I would get the gold. This is better that not trying and repenting later.
- You are trying to affect me psychologically. I will not switch.
- Probability that there is no gold in the opened cup before I open my cup = 1, because there is no gold.
So remaining probability that there is gold in the other 2 are 1/2 = 0.5 = 50% chance in both unopened cups.
I would like to switch because if I were to hold the other cup there is a probability that the cup that is going to be opened before I open my cup is empty again. The remaining cup would have the gold.
- I am optimistic and I think my intution is working. so I don't switch.
- I will switch. Because when I try to pick the first cup - he shows me one of the empty cups. Now I switch, whem I try to pick this one - he shows the other one. Thus I know the answer.