Latest CTS Aptitude Question SOLUTION: In a group of 80 coins, exactly one is counterfeit and weighs less than the others. U are provided a scale to weigh to coins. The min. no. of weightings req. to determine the count

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(#M40007332) CTS question Number problem Keep an EYE

In a group of 80 coins, exactly one is counterfeit and weighs less than the others. U are provided a scale to weigh to coins. The min. no. of weightings req. to determine the counterfeit coin is

a) 4 b) 1 c) 5 d) none of these

Asked In CTS (12 years ago)

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Tanuj Saini  (12 years ago)

a)4
27 27 26
9 9 9
3 3 3
1 1 1

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Debolina Pan  (9 years ago)

1st divide 80 coins in 2 groups,each having 40 coins.compare their weight take the lighter group(having 40 coins)
divide 40 coinns in 2 groups.similar after coparing their weight take the lighter group(having 20 coins)
divide it in 2 goups,take lighter group(having 10 coins)
divide it in 2 groups,take lighter group(having 5 coins)
divide into 3 groups,2 groups of 2 coins,and 1 single coin.
2 possibilities.
1.2 group of coins is of similar weight then,the lighter coin is the single coin.
2. if 1 of thos group is lighter than other take that group,and again divide it into 2 groups(each having 1),compare their weight,u will get the lighter 1

for the 1st possibility 5 comparisons is required,but for the 2nd possibility 6 comparisons required

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