There are 80 coins, among them one coin weighs less compared
to other. You are given a physical balance to weigh. In how
many wieghings the odd coin can be found.
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Answer / antariksh
divide coins into 3 groups,27,27,26.
1st weighing : first compare the weight of 27 and 27.If
they are equal then the third collection of 28 coins
contains the faulty coin else the lesser weighing collection
of 27 coins has the faulty coin.
2nd weighing : then divide the 27 coins into 9,9,9 of three
groups ,again compare the two 9's of them.if they are equal
then the third collection of 9 coins contains the faulty
coin else the lesser weighing collection of 9 coins has the
faulty coin.
3rd weighing : then divide the coin in 3 groups of 3.again
compare the two 3's of them.if they are equal then the third
collection of 3 coins contains the faulty coin else the
lesser weighing collection of 3 coins has the faulty coin.
4th weighing :now compare the two coins of them.if they are
equal then the third coin is the faulty coin else the lesser
weighing coin is the faulty coin.
| Is This Answer Correct ? | 58 Yes | 14 No |
Answer / amit mugal
Lets divide 80 into 27, 27 and 26
CASE 1: weigh 27 and 27.
IF weighs different, then next it wsll take 3 more times to get to the faulty one. So total of 4. END
Else same weight then count is 1 and take the sample of 26 den
CASE 2: Divide 26 into 9,9 and 8
Weigh 9 and 9
IF weighs different, then next it will take 2 more times to get to the faulty one. So total= 2+2=4. END
Else if same weight, then count 2 and take the sample of 8.
CASE 3: Divide 8 into 3,3 and 2
Weigh 3 and 3
IF weighs different, then next it will take 1 more times to get to the faulty one. So total= 3+1=4. END
Else if same weight, then count 3 and take the sample of 2
Now one more time weighing is required to find out the faulty one between 2 samples. So 3+1=4. END
| Is This Answer Correct ? | 8 Yes | 2 No |
Answer / saranya
The answer is 4....The minimum weighings required is 4.
Its like this...split 80 into 40 and 40 .We can find the the
40 which has the least weight.Next split this 40 into 20 and
20 ...Then split the one that weighed less into 10 and
10....Similarly We can find the one which is less by 6
weighing. But the answer is 4(The monimum weighing)
Can anyone tel me how?
| Is This Answer Correct ? | 18 Yes | 18 No |
Answer / ishu
Not less than 5 weighing and maximum 6 weighing
Answer no. 2 is not complete answer,the weighing will be
continue in 5-5.... and similarly 2-2......if both the two's
are similar then fifth is faulty coin, if one is less than
other then less weighted 2 coins will be weighted 1-1, and
less weighted will be faulty coin.
| Is This Answer Correct ? | 11 Yes | 12 No |
Answer / navya
First you take 30 coins and balance them with another 30. 20 coins are left "unweighd" If the weights are equal, you will have 20 coins left. Otherwise you will have a maximum of 30 coins left where the lighter coin is.
Take these 30 and weigh 10 coins against 10 (10 left over), and you will now have a maximum of 10 coins.
Take these 10, weigh 4 against 4 (2 left over), maximum 4 coins left.
Take these 4 coins, pair them up 2 and 2. Maximum 2 coins left.
Take these two coins and pair them up against eachother and you will find the lighter one
| Is This Answer Correct ? | 0 Yes | 1 No |
Answer / kapil sharma
it can be done in 3 ways.
First divide the coin in 20, 20 and 40
and then do it..
| Is This Answer Correct ? | 0 Yes | 2 No |
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