10 Bags Puzzle || Find the bag with defective coins

Counterfeit coin puzzle / riddle:
You have 10 bags of gold coins
each gold coin weighs 10 gm, except for 1 bag which has all defective coins(Counterfeit coins) that weigh 9 gm each.
However, all the coins (normal and defective) look and feel exactly the same.
Your task is to identify the defective bag with the help of a weighing machine that shows the exact weight in gram.
But the challenge is that you have only one chance to use this weighing machine to display the weight.
PUZZLE:
How would you find the defective coins bag(9gms) by using the weighing machine just a single time?
Watch the complete video for the solution.
Please like and share the video, also subscribe to this channel.
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Background Music Credit:
PACIFIC SUN by Nicolai Heidlas Music / nicolai-heidlas
Creative Commons - Attribution 3.0 Unported- CC BY 3.0
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Music provided by Audio Library • Video

[@random_pikachu]

you did not mentioned the total no. of coins in each bag....what if each bag have less than 10 coins in it.

[@LOGICALLYYOURS]

Hey Sandeep.. I agree brother, but the reason to avoid the statement "each bag has at least 10 coins" was that it could create a complicated statement. But it's nice to see that you pointed it out...

[@devondevon4366]

@@LOGICALLYYOURS but how would they know that each has at least 10 coins if not told?

[@amirkw123]

@@LOGICALLYYOURS You can say each bag has 100 coins

[@GabrielRFE]

We could solve it if we had 9 coins in each bag, by not counting a bag, if the weight is the expected, the bag that we didn't count has the fake coins

[@SgtSupaman]

Good riddle with interesting solution. I was just going to weigh one bag to see if it was the good or bad coins, then compare the rest of them by hand (if every coin in the bag is lighter, the bag should be noticeably lighter).

[@ujjaltodi830]

That was an amazing question.

[@shyamsharma1746]

It was really amazing...

[@sarvesh7kanojia]

At least mention each bag has atleast 10 coins. Puzzles do not have assumptions. Edit ur video.

[@devondevon4366]

exactly

[@ABCXYZ-zt3dr]

True

[@johnloukidis1579]

I had solved it some years ago after a lot of effort! I think it is masterful!

[@mdazharuddin3319]

out of the world......😲😲😲😲😲

[@onlinemathtutor7769]

it is superb puzzle.

[@aakritisunderum3921]

thank you very much for making this video. i have been trying to look for answer and its there on other sites too but only visually it has become more clear.

[@aakhyasharma9949]

Explanation! ❤

[@varijarana5638]

keep all bags on the weight machine at one time, then reomove them away from machine one by one.

[@ashutoshswain138]

No no , remember you have to weigh only once

[@varijarana5638]

Ashutosh Swain 🖕🖕

[@ashutoshswain138]

@@varijarana5638 dollard

[@abrarchowdhury2679]

@@ashutoshswain138 r/woosh

[@adityakuricheti6653]

Smart

[@mohamedsulaiman7410]

Super logic didn't thought of it

[@renukachhabra1815]

Really good and easy as well

[@ranjith.r9535]

Excellent

[@douglasfeather3745]

I don't your "optimal" solution is better. The solution with weighing 55 coins would also spot the case where you have been lied to and there are no bags with defective coins, thus I would argue that solution is better.

[@qurratulainfatima9322]

Awesome.. you really rock 👍🏻

[@LOGICALLYYOURS]

Thank you dear :) :)

[@nandapeela1080]

Fantastic bro

[@TravellerMann]

U r very optimistic bro

[@LOGICALLYYOURS]

Thanks for the appreciation Vishal :)

[@jagankhethavath5771]

Superb

[@venkannaca]

nice and good logic

[@gblargg]

And for good measure, double the quantities of each coin because the tolerances of the coins and scale's accuracy might make it one gram off.

[@mdmubashir743]

Amazing yaar

[@LOGICALLYYOURS]

Thanks Mubashir :)

[@nandapeela1080]

Awesome

[@Lol-wz2uw]

It becomes so much easier when you got a system to figure it out. but the hard part IS to figure out a system Sorry about my English not my first language

[@w0ttheh3ll]

A binary search would find the lighter bag using the scale 4 times at most, and 3 times if lucky.

[@neelpadia2307]

😉 One of the puzzles from , book My best mathematical and logic puzzles by Martin Gardner

[@vintagegame9]

The puzzle can work for both defects heavy or light at the same time.

[@bhuvaneshwarmanchala2942]

I had solved previously the same solution

[@PuzzleAdda]

Puzzle - A dealer has 1000 coins and 10 bags. He has to divide the coins over the ten bags so that he can make any number of coins simply by handing over a few bags. How must divide his money into the ten bags? Answer - kzbin.info/www/bejne/p6Cwmmeiip2Nrac

[@shubhamkohale9197]

Mahol bhai

[@LOGICALLYYOURS]

Thanks Shubham :)

[@mentor_neto]

open one bag and count how many coins are there. If it’s != 10, then put 9 bags in the machine if the total weight of 9 bags ends with 0, the remaining bag is the defective one. Otherwise, take one by one out of the machine, until the total ends with 0. The last bag you took from the machine is the defective one. The problem is if there is 10 coins inside each bag, because the weight will end with 0 too (90). But I’m sure you will figure out how to fix that.

[@anjanakeshari8420]

Take one coin from each bag , weigh all the coin together and keep the coins so that you can identify which coin is from which bag . Now remove the coins one by one . Whenever you remove a coin check if the weight is decreased by 10 or 9 gm , if it decreased by 9 gm it is defective and the bag cointaining it is also defective .

[@gabrielbarrantes6946]

That would be using it like 10 times

[@venugarg325]

How we know that bag have 9-10 coin atleast?

[@devondevon4366]

putting all 10 bags on the machine, then removing one bag at a time and whenever you have a zero as a unit digit while removing , then the bag in your hand is defective. so if after removing the first bag , 90lb is on the scale, then the first bag is defective and weight 9lb.

[@w0ttheh3ll]

take n coins from the n-th bag (starting with n=1) and pile them up until you run out of bags. put the pile on the scale.

[@LOGICALLYYOURS]

correct.. but one catch here.... don't take coins from last bag... because we also have to optimize the approach..

[@w0ttheh3ll]

@@LOGICALLYYOURS yes, if we are certain that exactly one bag has fake coins, that approach is faster

[@ayusheesahu5339]

I have another solution. (Not sure if this is accurate enough). Take out 1 coin from each bag and place it on the machine, one by one. The moment the reading shows less wt. , we can find out the bag with defective coins.

[@jay-oc5uc]

If that's the case then we can place every single bag on the machine not just a coin, but we need to place them on the machine only once

[@visiontvtelugu]

but you have to use and check weight only once rigth?

[@nidadursunoglu6663]

You can use the machine once

[@gharud_xd6812]

I have one another solution so took one coin form each bag and put your hand by same number and put it in row formation then remove one by one finnally you will get answer 😁

[@chandanameka2973]

great question bro

[@LOGICALLYYOURS]

Thanks Chandana :)

[@vinayakprabhu492]

What if each bag has only one coin?

[@sameeradhikari1777]

Wow

[@adamali-jr6ye]

Take one from each step by step then add on machine and check wait on each addition

[@Sadly_Simping]

Bruh you can only use it once

[@nitishsethi100]

Amar I have a more reliable approach , take one coin from each bag and put on machine. As all coin are 10 gram but one is 9 gram it show 99 gram now remove coin one by one. It always decrease by 10 gram if coin is perfect but in defective case it decrease by 9 gram.

[@deepakluitelDRL]

You took 11 weights, while removing coins, each time you are taking new weight. It's same as taking 10 weights

[@rajeshm9962]

From first bag take one coin, second bag 2coinns,,,,tenth bag 10 coins Now based on d wait we can find in which bag

[@Ryzler13]

Yeah, didnt mention we can take coins out of the bags.

[@dimitarliasovski8103]

it is same with 11 bags with 10 coins :D if is difference 0gm, bag is no 11

[@jessestefan6177]

I wish you would have specified that we can open the damn bags and weigh individual coins

[@FrozenHero2010]

The condition was to use the scales ONLY ONCE!

[@sasidharvivek5817]

Y I didn't get to this channel earlier

[@mihirbiswas5343]

I can not understand the second answer

[@vinaykamble1736]

I have another solution, we will kept all bags on machine at a time then total wt will be 99gm. Now we keep removing one by one and when we remove the bag of 9gm then total wt will be divisible by 10. So that will be defective one😏

[@visiontvtelugu]

the question it self says each bag has some coins. what if 9gm coins bag has 10 coins and remaining 10gm coin bags has 9 coins? then all bags are 90gm weight right? in that case your approach will wrong :-)

[@williamtraynor4350]

This solution is not for the purists because you are getting multiple answers so can be looked on as multiple weighings

[@w0ttheh3ll]

by the way, a gram is shortened to "g"

[@LOGICALLYYOURS]

you are right... my mistake

[@mohdtauheedkhan6198]

We cannot place all coins in one move

[@alexcruiser5277]

Bro I can identify defective bag without weighing Machine how??? I will take 10 coins from 10 bags and then take 2 coins from them and throw them from same height.10gm will reach ground first.and eventually I will come to know which coin is defective. explanation is based on Galileo s principle.

[@manaalanshath5079]

I did not get why he kept away the tenth bag. Can someone please help

[@mohitkumar-ph9tt]

i know this answer

[@moonyuen0505]

There is an additional question: there are 10 bags of coins but you dont know how many bags are fake coins. same situation , how can you solve that?

[@Nanda-cw3zj]

what if u werer given only a coinn from each bag

[@jisoolove229]

Impossible

[@BCS-IshtiyakAhmadKhan]

How can a man place 10 bags by taking respective no. Of coins in one attempt with just two hand's

[@casmartin790]

Yeah that's good n'all, but you know what would be easier? Putting all the bags on at once and removing them one by one to see which removal changes the scale by a different amount...Thinking inside common sense, not outside the box : )

[@ghazi5548]

What if we just place one coin from each bag and remove it one bye one When the weight shows 0 at last that will be defective coin.

[@sasidharvivek5817]

Long approach

[@marvinkitfox3386]

0:15 but you state that the defective bag has FOUR defective coins. You do not state how many coins are in the bags. This makes it unsolvable.

[@jessestefan6177]

He said ALL. I had to use captions too

[@marvinkitfox3386]

@@jessestefan6177 Contextually, "all" makes sense. That is also what the captions say. But what I hear is "four", on multiple retries on several different machines/speakers. So I asked a friend, and a neighbor. one of them is undecided. He simply cannot choose. The other is adamant that the word is "four" and cannot be anything else. My point: When the narrator has such a strong accent, he should employ additional visual aides to clarify. He is already displaying ALMOST all info. Why not expand the infogram to show all pertinent facts?

[@jessestefan6177]

@@marvinkitfox3386 agreed. His riddles are great. But he needs to work on delivery and narration as well as working on his accent. For me, I have an excellent ear for dialect, so I understand him perfectly even without captions. Except for the "all/four" part lol.

[@jvcbrasil]

sorry, but gram is g, not gm :) That confuses me

[@poonakutty6776]

Hi logically yours iam your fan i would like to convert your channel into my mother language Tamil if you like to convert kindly DM us

[@KoushikPaulliveandletlive]

From the first bag I wont take any coin, from the second bag onwards I will take like u have taken. 1 coin from the second bag , 2 coins from the third bag , 3 coins from the fourth bag and so on.... so I have to take 10 coin less than urs.

[@antinewbie]

Where's the difference to the solution in the video? You just named your bags differently

[@epicindiancomments9438]

Just Keep All The Bags on the machine And Take The Bags One By One out You will Get the defective one ( Why So Complicated )

[@sohailbasha7781]

but he didn't mention the no.of coins in each bag are same And if u remove one by one it means ur not measuring one time

[@sirpinkorange]

You can only use the scales ⚖️ once not 10 different times

[@benjyibreeg]

I figured it out but this is bullshit as 1.) The Problem doesnt say anyting about the amount of coins per bag and 2.) It doesnt say we can remove coins from the bags

[@shrutiagrawal3696]

not understood the logic

[@hovikgasparyan9729]

Are all your viewers Indian/Pakistani?

[@shubhamsemwal5532]

You didn't tell the solution correctly

[@shubhamsemwal5532]

The thing you are doing wrong to give the solution is that you are taking only 3 bags....instead we will take all 10 bags and put 1 coin from bag 1 and 2 coins from bag 2 and 3 coins from bag 3 and so on up to 10 coins from bag 10. Since all the defected coins are in the same bag. The weigh less than total 550 will show us the bag number. Like if there 6 gm less then all coins should be from same bag and 6 coins are from bag no. 6

[@neelpadia2307]

😉 One of the puzzles from , book My best mathematical and logic puzzles by Martin Gardner