Puzzle 10: A hen, a fox and a corn

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 Solution to puzzle 9

There must be a coin with value 5. Because to represent number 10 with maximum of 2 coins we need a coin of 5

There must also be coin of value 1 to represent number 1. 

To represent 9, we also need a coin of value 4 along with a coin of value 5.

So we must have coins of 1, 4, 5. 

Now to represent 3, we can either have a coin of 3 or two coins of 1 and 2. 

So the two possible answers are 1,2,4 and 5.  And 1,3, 4 and 5.

 With 1 2 4 5

1 -1

2-2

3 - 1 2

4 - 4

5 - 5

6 - 1 5 

7 - 2 5

8 - 4 4

9 - 4 5

10 - 5 5

You will also find such a representation for 1 3 4 5

Puzzle 10: A hen, a fox and a corn

This puzzle and it’s various versions are as old as me. It is no exactly a mathematical puzzle but a logical one. 

A farmer has to take a hen, a fox, and some corn across a river. The farmer can only take one thing across at a time. Unless the farmer's present the fox will eat the hen and the hen eat the corn. How is it done? 





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