One hundred pennies are on a table. Ten are tails.
With your eyes closed, can you separate them into two groups so that
each group has the same number of tails?
Here is the solution:
Take any ten pennies and turn them over.
They are group number one. The rest of the pennies are group number two.
If you don't believe that this works, try it!
Here is a table showing the possible coins that you could select for group one, and the resulting number of tails in group two:|
Group One (10 coins) If you select: |
Group Two (90 coins) | |
|---|---|---|
| 0 Tails | 10 Heads | 10 Tails |
| 1 Tail | 9 Heads | 9 Tails |
| 2 Tails | 8 Heads | 8 Tails |
| 3 Tails | 7 Heads | 7 Tails |
| 4 Tails | 6 Heads | 6 Tails |
| 5 Tails | 5 Heads | 5 Tails |
| 6 Tails | 4 Heads | 4 Tails |
| 7 Tails | 3 Heads | 3 Tails |
| 8 Tails | 2 Heads | 2 Tails |
| 9 Tails | 1 Heads | 1 Tail |
| 10 Tails | 0 Heads | 0 Tails |