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Question
```1)	You have 8 coins. 3 of them weigh x units, 3 y
units, 1 a units and 1 b units. They are all mixed and look
identical. You have to find the lightest coin in minimum
number of weighing .```
Question Submitted By :: Luvsaxena
I also faced this Question!!     Rank Answer Posted By

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 1
3

1. 3 coins of x unit on 1 side and 3 coins of y unit on the
other (let winner is x)

2. a coin of a unit on 1 side and a coins of b unit on the
other (let winner is a)

3. a on 1 side and x on the other (winner declared)

 Is This Answer Correct ? 11 Yes 25 No
Pratik

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 2
Pratik
You are a pin head. All the coins look alike. How will you
select the x,y,a and b units?

 Is This Answer Correct ? 27 Yes 5 No
Anan&039;s Math Teacher

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 3
Weigh X and Y. And see which is the lightest.
take the lightest of X and Y and weigh it against A or B. See which is the lightest among them and weigh it against the remaining coin.
So the answer is 3 weighs.

 Is This Answer Correct ? 2 Yes 13 No
Shreyas

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 4
Shreyas, you don't know which is x and which is y (since
all coins are alike) , that was mistake i was doing before.

 Is This Answer Correct ? 5 Yes 4 No
Pratik

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 5
They look alike means that they are identical in size and shape.
It can still be named as X, Y, A and B.

Its like Rs.1, Rs.2, Rs.3 are in the same shape and size. But you can tell which is what.

 Is This Answer Correct ? 4 Yes 7 No
Shreyas

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 6

We will use a weigh measurement machine.
Initially, it will show weight @ zero. Now start putting coin one-by-one and measure the weight every-time a coin is placed. Where the difference in unit weight is minimum, then that coin will be the lightest.
Eg. when coin 1 is placed- total weight = 30 gms
when coin 2 is placed- total weight = 40 gms (cumulatively)
when coin 3 is placed- total weight = 45 gms (cumulatively)
So the lightest coin is 3rd coin.

 Is This Answer Correct ? 5 Yes 10 No
Gaurav Dhawan

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 7
We can make pair of two. Then out of each pair, find out the lightest and then form two pairs. Again find the lightest coin in each pair and then form a pair of obtained coins. Lightest of these two is the one required. Total 7 steps. I think this is the answer.
 Is This Answer Correct ? 4 Yes 3 No
Ankita

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 8
as there are 8 coins..put 4 on one side and the other remaining 4 on the other side.. obviously one side will be lighter..
now the possible combinations of coins which can be on the lighter side are:
1)x,x,,x,a 2)x,x,x,b 3)x,x,x,y 4)x,x,y,y 5)3)x,x,y,a 4)x,x,y,b 5)x,x,a,b 6)x,y,a,b 7)x,y,y,a 8)x,y,y,b 9)x,y,y,y 10)y,y,y,a 11)y,y,y,b 12)y,y,a,b

well whatever the combination be, you need to divide it again into a group of 2-2..you will again get a lighter group..finally compare the last two coin and u will get the lightest coin of the 8 coins given...
so, that makes a total of 3 steps..
thumbs up..!! :)
# refer the above possibilities to get a clearer picture

 Is This Answer Correct ? 1 Yes 4 No
Dinesh Thouna

Re: 1) You have 8 coins. 3 of them weigh x units, 3 y units, 1 a units and 1 b units. They are all mixed and look identical. You have to find the lightest coin in minimum number of weighing .
# 9
Hi Dinesh,

This is regarding ur above answer.

i think u are wrong.

Step-1 is ok.
Step-2 is not - Plz see explanation below.

When in step-2 u divide 4 coins in 2 pairs, it is not necessary that lighter coin will be on the lighter side, it can be on a heavier side for ex -

there r 4 coins, their wts are 2gm, 8gm, 3gm, 4gm

put them in balance- 2gm and 8gm on 1 side
3gm and 4gm on other side.

now the lighter coins is in heavier side, now u have ignored this logic. try something new buddy!!!

 Is This Answer Correct ? 3 Yes 1 No
Pratik Taank

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