Question

Из 15 монет одна фальшивая неизвестно она тяжелее или легче как узнать сделая наименьшее количество взвешиваний фальшивую монету друзья миленькие помогите

Answer 1

Разделить монеты на 7, 7 и одну. Всзвесить кучки по семь, если масса равна, то отложенная монета фальшивая, иначе берем кучку которая оказалась легче, делим на 3, 3 и 1, аналогичным образом взвешиваем. Если фальшивая монета в одной из кучек, то делим её на 1, 1 и 1. Взвесив две мы точно узнаём фальшивку. Итого: максимум 3 взвешивания.

Answer 2

Solving the Coin Riddle

To determine the fake coin among 15 coins, whether it's heavier or lighter, we can use a balance scale and a strategy called "divide and conquer."

Here's how to do it:

1. Divide the Coins into Three Groups: - Divide the 15 coins into three groups of 5, 5, and 5.

2. Weigh Two Groups: - Weigh any two of the groups against each other. - If the two groups weigh the same, the fake coin is in the third group. If one group is heavier or lighter, the fake coin is in that group.

3. Weigh Two Coins: - Take the group with the fake coin and divide it into two groups of two coins and leave one aside. - Weigh the two groups of two coins against each other. - Based on the result, you can determine which coin is fake and whether it's heavier or lighter.

By following this strategy, you can identify the fake coin using only three weighings.

This method ensures that the fake coin is identified using the minimum number of weighings possible.

I hope this helps! If you have any other questions or need further clarification, feel free to ask.