Defective stack of coins puzzle
1,461.3K Views
There are 10 stacks of 10 coins each.
Each coin weights 10 gms. However, one stack of coins is defective and each coin in that stack weights only 9 gms.
What is the minimum number of weights you need to take to find which stack is defective? How?
SOLUTION- 1 Measurement Only
EXPLANATION-
We will take,
1 coin from the first stack,
2 coins from the second,
3 from the third
and
so on.
In total we will have 55 coins.
If all of them were non-defective, they would weigh 550 gms.
If stack 1 is defective, the measure would read 549 gms.
If stack 2 is defective, you will read 548 gms.
and so on.
So by taking one measurement you can identify, which is the defective stack.
Your Answer
More puzzles to try-
Divide the components evenly
A man is the owner of a winery who recently passed away. In his will, he left 21 barrels (seven ...Read More »What color is the bus drivers hair?
You are driving a bus. At the first stop, 2 women get on. The second stop, 3 men get on ...Read More »When parachute doesn\’t open
What do you call it when your parachute doesn\’t open?Read More »What does it’s represent?
1. What does: TIM JOB represent? 2. What does: MO_ _ represent?Read More »What is Before You
During an interview, the interviewer ordered hot coffee for the candidate to relieve the stress. The coffee was kept before ...Read More »Dial Police 911
On the dull night when the blonde was dozing, she heard an odd clamour and she saw that there was ...Read More »Crack this question
Bay of Bengal is in which state?Read More »Coin Toss investigation puzzle
A dead body is found at the bottom of a multi-storey building. Seeing the position of the body, it is ...Read More »Most Difficult Induction Teaser
A teacher decides to give a pop quiz one day but all of her students refuse to take the quiz ...Read More »Candies interview puzzle
In a closed jar, There are Three strawberry candies, Two mango candies and Five pineapple candies. You can’t see inside ...Read More »Falling from Ladder
A boy fell off from a 50 feet ladder, but he did not get hurt. How is this possible ?Read More »Statements Puzzle
The pound is not a finish. We are sharing a few instructions below, which you have to use in any ...Read More »What is red and smells like blue paint?
What is red and smells like blue paint?Read More »Head and Tail Story
I possess a head I flaunt a tail But I don’t have mouth or legs Can you find out who ...Read More »Who is the killer ??
There are five people. One of them shot and killed one of the other five. Which man is the murderer? ...Read More »Find the amount
I bought a sari and a blouse for Rs. 110 at the New *Market. The sari cost Rs. 100 more ...Read More »Prime Pairs riddle
Pairs of primes numbers separated by a single number are called prime pairs like 17 and 19. Prove that the ...Read More »Forward I am heavy, but backward I am not riddle
Forward I am heavy, but backward I am not. What am I?Read More »Pizza Cost Math Brain Teaser
Jasmine, Thibault, and Noah were having a night out and decided to order a pizza for $10. It turned out ...Read More »Parrots and Rabbits puzzle
There are several Parrots and rabbits in a cage. There are 72 heads and 200 feet inside the cage. How ...Read More »
Accenture Interview PuzzlesAdobe Interview PuzzlesAge RiddleAkbar Birbal PuzzlesAlgorithm PuzzlesAlphabet riddleAmazon Interview PuzzlesAnalytical MathematicsAptitude PuzzleBank PuzzlesBetting PuzzlesBrain TeasersCalendar PuzzlesCards PuzzlesChess Board PuzzleChess PuzzlesChristmas Puzzlecipher PuzzleCivil Services PuzzleClock time puzzleCognizant Interview PuzzlesCoins PuzzleComputational PuzzleconundrumCoronavirus PuzzleCoupondunia Interview PuzzleCritical Thinking Puzzledata analyticsData Structure Interview QuestionsDecode PuzzleDetective PuzzlesDice PuzzleDictionary Riddlesdifficult riddleEasy Math puzzlesEasy puzzlesEinstein puzzleEnglish RiddleFamily Tree Puzzlefamous puzzleFill in the blanks riddlesFinding Killer RiddlesFlipkart interview puzzlesFunny RiddlesGeneral KnowledgeGeographical PuzzleGoogle Code Jam 2014Google Interview PuzzlesGRE PuzzleHard Puzzle