Btw, I will place the answer for the previous question and the following question under this comment. But try to refrain from look at it yeah?
Beanie asked me this qns yesterday: " Suppose you have 12 coins, and 1 of them is a fake. This fake can be lighter or heavier than the rest of the coins. And suppose you have a balance scale; how can you determine a)which is the fake coin and b)whether is it heavier or lighter in only 3 tries?
I solved this in 15mins, but not very sure of the answer. Feel free to correct me. =)
Monday, March 9, 2009
IQ coin question
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4 comments:
Einstein question : The german who owns the green house, drinks coffee and smokes prince owns the fish!
IQ coin qns:
Let the weight of each 11 real coins be y and fake coin be x.
a)Suppose x < y, in the fast try of balance scale, 5y+1x < 6y, hence we can isolate the 6 coins with the fake coin.
b) Further split into 2 groups, 2y+1x < 3x.
c) Lastly, take random 2 coins and weigh them. If they are equal, means the last coin is fake. If 1 is lighter than the other , then fake coin is determined.
Can also work from a) to c) in such method for a heavier fake coin.
"Ng Yeong Boon Roger" likes this.
wont you be weighing 6 times? i got the same answer as you in one min. lol.
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