Dark Room and Coins Puzzle || Amazon interview question

It's an Amazon interview question. In a dark room, where there is no light at all
35 coins are scattered on a table.
Exactly 10 of them have heads facing up.
There is one more table in the room.
How do you move coins from the first table to the second table…
so that there are equal number of coins with Heads facing up on the two tables ?
Instructions:
Due to darkness, you cannot see the coins.
Also, you cannot feel the texture of the coins
Hint:
The total number of coins on both tables need not be the same
Only the number of coins with 'heads facing up' needs to be the same
Watch the video for the explanation.
It's one of those questions asked in amazon interview that is desinged to check logical thinking and lateral thinking of a candidate.
On my channel LOGICALLY YOURS, you will find many puzzles that are focused on various skills such as logical reasoning and analytical reasoning. These puzzles and riddles with answers will also improve your critical thinking skills test .
I will be posting some intersting brain teasers and interview puzzles from Amazon bar raiser interview.
Also, try difficult puzzle on this channel:
Cheryl's Birthday Puzzle || Viral Puzzle on Facebook and Whatsapp
• Cheryl's Birthday Puzz...
Two Cubes - Calendar Puzzle || Can you solve ?
• Facebook Interview Puz...

[@pratikmaity4315]

Here is a proof of why his method works:there are 10 H coins on table 1. Now we pick any 10 coins from table 1 and place those on table 2. Suppose we picked x no of H coins and 10-x no of T coins and put then in table 2. So now we have 10-x no of H coins in table 1. Now if we flip the coins in table 2 then no of T coins will become no of H coins=10-x H coins. So we have 10-x H coins in both the tables. Awesome puzzle and solution!!

[@LOLO-yk8qc]

I have a doubt y can't he just throw all the coins down so that both table have 0 coins facing head as well 0 on each😂😂😂

[@abinashsatapathy3348]

Here already written :you can move the coins to 2nd table

[@sensei.0909]

But it is nice thought

[@harshrajsharma5050]

I was going to comment that

[@arbazulmalik4500]

you can get selected even after giving this answer! they will appreciate.

[@beautyofinfinity2024]

🤣🤣🤣🤣

[@fizixx]

I first saw this many years ago. It was a fun 'magic' trick, however it was done with 7 coins and the coins were covered with a cloth. You were to reach in and make the switch 'sight unseen'! It's an impressive trick. Problem was, I lost the trick somehow, forgot about it and could never find it again. It didn't really have a name, and searching for 'coin tricks' brought up way too many to search for. Eventually gave up looking and I could not figure out how it was done. I was unhappy with myself because of it. Then here you are with essentially that same trick! Many, Many Thanks! subscribed :)

[@LOGICALLYYOURS]

Welcome to the channel :)

[@devendrapatel197]

Wow man I am addicted to your channel...keep up bro,,

[@LOGICALLYYOURS]

Highly appreciated :) that really gives inspiration to make more and more videos.

[@rameshthakur3185]

You are making us logically yours

[@vsrinivas1973]

Of course; please don’t quit making videos; I am addicted to them too and I like your explanation; which inspires me to become more and more logical…

[@bhanunegi4074]

I know this answer is not good but..... I think it is also a correct answer On the table which have 35 coins.... Throw all the coins to the floor... Now both the tables have equal number of heads that is 0. 😀😂

[@Pokymons]

Nice 😂😂

[@kuls43]

He has asked to move coins to other table.

[@eminemmarshall7689]

Gr8....U r Genius....I'm a student of physics n interested in Maths....u R simply Awesome...Hatssoff...!!!

[@deeprajmandliya1777]

In the 2 coins case is there no guaranty one coin is with head face and another one is tail face so when we pick up one coin and flip them that coin will be unequal number

[@LOGICALLYYOURS]

Hey Deepraj.... if you have two coins (one head-up, one tails-up), flip anyone while placing on second table... and you will either have one heads-up on both tables... or zero head-up on both tables... in any case they are equal.

[@deeprajmandliya1777]

My que is if both the coins are with same face then we pick up any one and flip them then they are unequal

[@shreenabh]

LOGICALLY YOURS His logic is right... What will be the guarantee that one of the two will be head a ND other will be tail?

[@knightofchaos4647]

I think you've missed the part where he states "consider exactly 1 coin has heads facing up". This is an important part to understand the logic used in solving the problem. You could also state the same thing (meaning no guarantee about how many coins are heads up) about his 5 coin example where exactly 2 are heads up.

[@marmiksharma2573]

Dude you've misunderstood. In each case we will know the exact no. Of heads initially present. Hence if we have two coins and they say no head is present then it is certain that both are tales. And if they state 1 H is present then further procedure is same.

[@afreenshaikh3888]

If I can't see or feel texture of coins how am I able to know that the coins I am placing on second table is head or tail

[@kishlayamourya3141]

U dont need to know that....just take any 10 random coins and flip them and put them on 2nd table....

[@HALLvsTON]

@@kishlayamourya3141 puzzle is "Only the total no. Of coins with heads facing needs to be the same". Then how can you just take randomly pick and flip the coins and place them on table? This is not correct. It's just impossible. Coz there must be equal no.of coins facing heads on both the tables. 😐😐😐😐😐

[@ankursinha95]

@@HALLvsTON there is equal no. of heads facing up even if you pick any 10 random coins. You can try any combination. It will always work. Try yourself if you're not getting it.

[@adityasutar9436]

@@HALLvsTON look think that u picked 10 random coins in which 3 are head up (means 7 heads remaining on first table) then flip and put on other table there'll be 7 heads that is equal to first table heads up.... Try for other combination you'll get same result

[@shivamkatiyar2899]

Try it at home 😄

[@swamy8baba]

Again awesome!!!!!!

[@AmanKumar-fd5ec]

Please make video is this puzzle named Chaos in the bus: There is a bus with 100 labeled seats (labeled from 1 to 100). There are 100 persons standing in a queue. Persons are also labelled from 1 to 100. People board on the bus in sequence from 1 to n. The rule is, if person ‘i’ boards the bus, he checks if seat ‘i’ is empty. If it is empty, he sits there, else he randomly picks an empty seat and sit there. Given that 1st person picks seat randomly, find the probability that 100th person sits on his place i.e. 100th seat.

[@RedXLink]

This was an incredible riddle! I came close to the answer but didn't think to flip the coins each time you move them. Really awesome solution!

[@Kricka91]

Alt. solution 1: Put all the coins on their side (edge) on either table, now you'll have exactly zero coins with the heads side up on each table. Just make sure they stay on the tables if that's a requirement. Alt. solution 2: Move the tables together so that their edges touch each other. Now stack all the coins on top of each other and place this single stack of coins on this border so that it sits on both tables at the same time. Now each coin with the heads side up will contribute to the coin heads count on both tables. (Of course, this requires the tables to be of the same height.)

[@vineetksirohi]

To cover the case of 0 heads up coins, transfer half of the remaining coins to table 2 and flip them (In this case 25/2 = 12). Take 12 coins on table 1 and flip them too.

[@vasanth_zoldyck8623]

The condition is only the number of heads are need to be equal and the number of total coins on each table does not have to be equal so if there are no heads on table 1 you don't even have to move a single coin to table 2 cuz technically there are 0 heads on table 2 also .... But I appreciate your thinking ❤️

[@becalmandquiet881]

Great video

[@parteeks9012]

I got this question in an interview !! now seeing it here makes me waana watch all videos of your channel!!!

[@tharundharmaraj9045]

Super explanation sir...

[@illusion9777]

My method ( just flip coins in a way , 1st coin should be flipped 2nd should be same , 3rd should be flipped , 4th would be same , and so on until 20 coins)

[@Snowball_the_bernard]

I exactly solved the answer with the same approach as urs😋😁😁

[@zukaka84]

You move 10 coins. Then the first table will have x amount facing up and the second table will have 10-x facing up. Flipping all 10 on the second table will make 10-(10-x)=x facing up. I directly solved like this instead of starting with smaller numbers.

[@alexbrots803]

HEY so sorry to bother but do you, or anyone else here, know the original study where they put "two" teams in a dark room with a puzzle and a loud buzzer and the scientists in a different room and are buzzing them to get their reaction to see if some people are more aggressive than others? its a psychological study! PLZ HELP IM WRITING A PAPER DUE TONIGHT!!! thank you so much!

[@gourabguha3167]

Supposedly​ you move 25 coins from table1 to table 2 and coincidentally all the coins were heads facing down in table 1. So, on moving them to table 2 they become heads facing up. So table 2 has 25 coins heads facing up and table 1 has 10 coins with heads facing up. So your solution fails in this case. Can you justify or give a better solution???

[@ankursinha95]

Suppose the no. of heads up coins on table 1 was 'x'. So you have to move only 'x' random coins and flip them. You don't have to move more or less than 'x'. If you move more or less, then the solution will fail. The solution to this puzzle is that whatever number of heads up coins is given in the question (here 10) you will move that many coins and flip them.

[@supersonic6734]

Woww...

[@getsetquiz1452]

simply awesome

[@beobeo851]

take 10 coins and flip them over.let's say that you got 3 "heads up"the first time,the number of remaining=10-3=7.when flipped:7 heads and 3 tails to match 7silver.we can prove this using Algebra: s1(pile 1)=20-n g2=20-n \flipped: \g2=s2 \s1=s2=20-n pile 2

[@LOGICALLYYOURS]

Hey Tuan... thanks for sharing the approach(try to generalize for x number of coins instead of 20.)... I really enjoyed understanding the equations as the title for variables was not mentioned.

[@chetankarkera2477]

One suggestion - You can divide your videos in categories levels . e,g Easy, medium, hard, expert.

[@YGaming18]

will explained thanks

[@shrutikanalawade5636]

oh no!!!! really it's Awesome!!! you are a genius

[@HARSHITKUMAR-wj4ex]

Your work is highly appreciated , Keep up the good work!!!!

[@adarshranjantripathy5562]

really nice logic......you are just a professional in solving puzzles :) ......

[@LOGICALLYYOURS]

Logically Yours :D :D :D

[@williamturner6192]

Trick question, humans and robotic drones both emit some type of light so neither I nor a robot drone acting in my behalf are in the room. But if I assume no viable light and I have no goggles for the purpose... My guess is you want me to flip them before placing them on the tables but that would not make an even distribution.

[@williamturner6192]

Oh, I can just throw them all off both tables, duh!

[@karthikm8679]

Nice puzzles sir.

[@sachinmotwani2905]

Nice one..

[@knighthonor44]

or just knock all coins off first table and now you have same number of heads up coins on both tables, aka Zero

[@lasyagajavelli594]

It's awesome

[@anirbandas3704]

Hats off ..I thought it impossible. Untill I came to know about the answer

[@sagardam2989]

this is awsome

[@mohit12aExp]

Amazing sir

[@dhiraj.govindvira]

jakas ... keep it up ..

[@R_samurai779]

Man this is awesome.......first....I di not even understand the questiin properly...but the answer was quite simple!

[@LOGICALLYYOURS]

Thanks Amit

[@samrwil]

Blew my mind

[@tericosimpson945]

I guess in theory it works, if the conditions are perfect, but realistically you could grab all tails and if you only flipped two, you'd still have 8 heads up coins on the other table.

[@chirag_soni_07]

Mindbolwn

[@adiosamigo1988]

Noone says all other coins are tails. They may be on the side or in superposition. Noone says, that all coins have one head and one tail side. Anyway solution: move all coins out from table. 0 is equal to 0.

[@dr.riddle6392]

nice puzzle... i like it much.

[@sukhandeepsingh7573]

Very Enjoyable Game

[@rajeshm9962]

Pick 10 coins from from first table and keep it reverse on another table I saw this kind of puzzle using playing cards....

[@Akshay-ji9nt]

Damn that was a tricky one

[@Akshay-ji9nt]

Same thing can be done with face up and face down cards

[@SunnySharma-jc9ln]

It's was really very very interesting and tricky

[@shreyartz1697]

ITS WONDERFUL LOGICAL VIDEO BRO.

[@sowmyasudhir2600]

Super questions man

[@aliflowerorangilo4747]

Got it. Yahh

[@yuvraj6279]

Your videos are awesome bro. Keep up the good work and thank you so much.Waiting for more videos😊

[@srishtychaudhary4622]

But here we have a darker room and we can't feel the texture of the coins then how will we know whether the coin is head faced or tail faced after moving.

[@manooruvinoda4555]

Yes

[@albertreyes9870]

This guy is Crazy.

[@purusottamvishwakarma1480]

Sir how to solve the puzzle......If there are two coins on the table with heads facing up on both the coin and then if one shifts any one coin from one table and puts it on another table by flipping it then on ist table there will be one head and on 2nd table there will be one coin with tails facing up....and no of coin with with heads facing up will not be equal?

[@jujharsingh6462]

Wow...

[@lasanthaprabodha6529]

Wow.... I didn't know this. Thanks a lot

[@Hasan...]

My solution was slightly different but also works, and it doesn't require flipping of coins either.. I would first switch on the lights, and move 5 Heads on the other table. Just like you never said you can flip the coins, you also never said you can't turn on the lights. :)

[@swetabjahazra8050]

Very nice channel. Keep up the good work...

[@kunalkundwani4915]

This question is of Pre RMO or RMO level I loved the question Thanks!!

[@abhishekbhushan2684]

yaar laate kaha se ho....jo v ho mzza aa jata ....i subscribed only 4 channels on you tube,and Ur channel beating all.

[@ajaykumargupta8504]

Cool

[@aafreenrah5135]

Thanka for sharing!! Really challenging..

[@PraveenKumar-ft2kr]

Awesome 💥

[@adarshpnair7876]

In your 2nd example what if the man select 3 coin out of which 2heads and 1 tail ... Then it will become inequal

[@dougaltolan3017]

Solution 1: tip all the coins on the floor Solution 2: put table 1 on table 2

[@amalnn8979]

I got it ✌🏻...

[@divyam_rathi]

Superbbbbbbb

[@vinithkumarsubramani1996]

Keep on doing man...u r something different level...

[@LOGICALLYYOURS]

Thanks Vinith for your kind appreciation : )

[@keyzer380]

Always missing crucial informations... Like you have the right to flip the coins and the heads up coins do not need to be the same from the beginning

[@priyanshiagarwal2291]

I solved this😀😀😀😀

[@laxmangorinkala4068]

Really... Great brother!!!!

[@cjfdnqkn4374]

I'm gonna subscribe ur channel

[@renanith]

beautiful

[@danishnisar8775]

Marvelous bro.. I like it..😱😵

[@LOGICALLYYOURS]

Thanks Danish

[@aadhithkrishna5682]

My doubt is, u said it is dark.So how can u know where those 10 H coins are in T1? If u take any random coins as to be flipped, then why cant i say all the 10 were tail facing up. How this puzzule is sloved without touching clarifications for my(kind of) questions???,.

[@darkking8686]

I'm loving it bro keep it up

[@photon77]

I have done this according to your answer using coins practically.....And it didn't work. We will understand better when you will put a real life video solving the puzzle

[@monolizm]

curious being can you provide more detail?

[@manishbolbanda9872]

tysm

[@katrawathdivya8066]

If i move 10 coins ..in that 6 are heads 4 are tails suppose...if we flip them it becomes 6 tails 4 heads ..then on other table 6 heads will be left ... Which makes it unequal.

[@swethasri5776]

,1st of all in that dark how could we know which 10 coins are facing heads up in order to equalise the heads on 2 tables

[@battulasai1619]

if u don't feel the texture of the coins, then how would know us to flip coins make it an equal number of heads. anyhow, we can't see them bcz it was a dark room.

[@sumitborde3131]

ty bhai

[@YaminiX]

What if i just put all the coins on the second table without flipping them

[@smslca]

Generalized answer: if you have N head faced coins and you also have N+T tail faced coins , for T>0 then pick any of the N coins at random onto table2 and flip them. You always find equal number of heads on two tables.

[@manikantakedarisetti2550]

I've a doubt if I flip only tail coins or above 10 number of tail coins on the other table then the number of head faced coins on the two tables are not same

[@vamshikrishna8979]

Consider 3 coins heads facing up how to make heads equal on both sides..

[@vigneshr8956]

I ll show this as a magic,lol😎

[@samakshgupta4472]

Superb Man...Best Puzzle...From where u get such inspirations??? Do Answer :)

[@LOGICALLYYOURS]

Thank u Samaksh :) I have been solving puzzles since childhood, but I feel explaining the puzzles is even more fun :)

[@praveendoshi1975]

New riddle A cricket match is going, 1 wicked left, 3 ball left and 7 run required to win. Players on Cris both scored 94-94 run, both have to complete century. And win match. Question is how they can

[@renukajoshi3854]

first I thought I won't b able to solve it... may b it's a probability /pnc question ... but than just trying it, I got the solution 😄😄😄 feeling like genius 😅😅 though I know it's not a big deal ... anyways I loved this riddle ♥

[@LOGICALLYYOURS]

Perfect :)

[@notayushforsure]

Sir u r great... what's ur age and where do u live

[@LOGICALLYYOURS]

Thanks Ayush for the appreciation :) I am 30.. from Hyd

[@vijendramalik5965]

How do we know that we are moving coins that have head or tail on them to the second table, as there is no light in the room at all. We can't tell which coin, wether head or tail , we are moving to second table.

[@kuls43]

I thought something is wrong with me that I am not able to solve these puzzles but now I am relaxed. Guys are not able to understand the solution 😂 You don't need to know, you just need to move 10.coins to other table and flip them.

[@minturoy31]

It was easy btw .😍

[@dhwajgupta1738]

i think flipping as an option should be mentioned.

[@goguhu]

Just move 10 over and flip them all? If you happened to get all 10 H you now have 0 H on both tables ... If you happened to get 3 H and 7T you end up with 7H left on the old table and 7H on the new table. If you get 0 H and 10T you end up with 10H on both tables.

[@AJ-rj6ee]

The instructions says that you cannot see the coins and also can't feel the texture...? 😕

[@manurohit6867]

How would know in darkness whether it is facing heads or tails while flipping

[@kuls43]

😂😂😂

[@KoushikPaulliveandletlive]

This one was easy, I lost in the "fox and five hole " one

[@manusarda]

Hole*

[@lukaeric3359]

I solved It ,am I genius?