Tuesday, May 09, 2006

Brain teaser

Finally decided to get up today and its already 3:30pm. I was catching up on some jokes and I came across this brain teaser:

Which of the following statements is true?

1. One of these statements is true.
2. Two of these statements are true.
3. Three of these statements are true.
4. Four of these statements are true.
5. Five of these statements are true.
6. Six of these statements are true.

Thinking about this one, I found starting from #6 would be easier rather than number one. For #6 to be true, that means obviously all 6 have to be true including number 6 which contradicts all the other 5 statements so #6 cannot be the true one. Move on to #5, if #5 is true then 4 other statements must be true, since #6 is false then statements 1-4 must be true, but that contradicts with each statement itself so #5 cannot be true. Repeating this until we reach statement #1. By now it is clear that only one of these statements can be true while the rest must be false otherwise that true statement contradicts what is mentioned in the other statements. Thus, statement #1 is the true statement!

Now that was an easy brain teaser. Hmm..what now..?

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