Find the fake coin

Moto Hell - The Motorola Modding Community

April 27, 2024, 02:09:18 pm

Welcome, Guest. Please login or register.

News: The forum is no longer active and registration is disabled; however you can still fetch everything as guest.

Home

Help

Facebook

Calendar

Moto Hell - The Motorola Modding Community > General > Off topic > Find the fake coin

Pages: [1] Go Down

« previous next »

Author

Topic: Find the fake coin (Read 4361 times)

Exploited

Administrator
Ultimate modder

Karma: 108
Offline

Offline

Posts: 5153

Find the fake coin

« on: October 11, 2007, 10:06:20 am »

You have nine visually equal coins, but one of them is fake and it is a little bit lighter than the others. You have a precision scales, but you do not want to loose many time and you preffer to find the fake coin with only two weighs. Please describe how you can find the fake coin with only two weighs...


	Logged

Philip Petrov - C/C++, PHP, MySQL and others

BlinK_

Guest

Re: Find the fake coin

« Reply #1 on: October 11, 2007, 11:30:27 am »

1. Arrange all coins in groups of threes.
2. Pick any two groups and put them on the scales.
3a. If scales show that these groups are equal then pick any two coins from group whitch was left and put them on the scales. If one coin is lighter than another then it is the fake coin. If they are equal, fake coin is the coin left unscaled.

3b. ELSE If scales show that one group is lighter than another, then pick any two coins from lighter group and put them on scales. If one coin is lighter than another then it is the fake coin. If they are equal, fake coin is the coin left unscaled.