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Saturday, June 10, 2006


ALRIGHT. This is my 1st post . So let me start with a appetizer. This is a little brain teaser that I put to u.

There are 10 matchbox containing 10 matchsticks each. Each mathstick weighs 10 grams. One box is defective where each stick weighs 11 grams. Given an electronic weighing machine and one chance to use it how can u dertermine which bix is defective ? U are allowed to take out sticks from the boxes


zinx said...

OK plz forgive my spelling errors!

Gr81 said...

lol Started with an easy one, eh?
So shall I write the answer rite now (too soon?) Well take 1 stick from 1st box, 2 from 2nd... 10 from 10th.
Now had there been no defect,we would have weight= (1+2+3..+10)*10 = 550gm.
So if actual weight is 556 (say) then the defected box is 6th (coz their weight will be 11+11.. 6 times)

Another similar one: U have 9 coins, one of them being heavier than the rest of equal weight. So, given physical balance, (or taraju - not very hi tech!) Find the heavier coin by using the taraju only 2 times..


sparekh said...

not fair rash. sjouldn't have made the answer public. but you left another prob, so i'll forgive you.

you divide the nine coins into three groups of 3 coins. and but 3 coins on each of the pans. if they balance the defective one is among the other 3. if not the heavier group of coins is the one containing the defective one. so take two coins from this group and put one each on the pans. and then apply the same logic.

Gr81 said...

Well done parekh!
But, I had left another ques coz it wasn't fair to write the ans so soon - but y didn't u leave another ques??

And yeah, Where are the others?
Watching Cricket? (Ok Ok I know you aren't that mad, are you?)
Or Watching World Cup?? (Now thats a good excuse - but atleast you are free in the afternoon!)

So post - reply - chat - comment and keep the blog active!
ApNe SoE HuE ScIeNtIsT Ko JaGaO!
AuR FuSeD BuLb MeIn BaTtI JaLaO!