Answer
$32$ players
Work Step by Step
The initial number of players is $800$.
Each round, the number decreases by $30$ percent, or per round $800$ is multiplied by $0.7$.
The number of players by the ninth round must be predicted, thus $800$ is multiplied by $0.7$ as much as $9$ times.
This can be expressed as:
$800×0.7^9≈32.$
