How it works
Nobody can know which garden will win, and last year's winner may not win next year. If all 100 coins sit in one garden, it could leap to 140 or shrink to 50.
The basket keeper put ten coins in each of the ten gardens, so Ana's hundred was spread out.
The basket follows a list of gardens, and that list is called an index. A basket that follows the list with no guessing is an index fund.
A basket is not magic: in a hard year most gardens fall together, but it falls less than one bad garden might.