The coin blunder
You have been given a beam balance.You also have 59049 coins, out of which 1 coin is defective.The defective coin is lighter than the rest of the coins.You have to pay $1 for every use of beam balance.You have to save money as much as possible.How much you will pay in $.....
Hint : Factorize 59049.
The answer is 10.
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1 solution
5 9 0 4 9 = 3 1 0
To find the defective coin we must divide it into groups. If we have to find the answer in less use of the balance we should divide into three groups each having 3 9 .
Then we will take any two and measure it in the beam balance. The lighter one contains the defective coin. But if it is equal in weight then the third one contains the defective coin.the we will repeat the steps untill we are left with 1 coin. So we have to use it 10 times and pay $10.