$\"\"$

In the sequence $\"\"$ , $\"\"$ and $\"\"$ .

Find the common ratio.

$\"\"$ .

The common ratio is $\"\"$ .

Find the sum of the series.

Formula for the sum of a finite geometric series is $\"\"$ .

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

$\"\"$

$\"\"$ .

Including Cora, $\"\"$ people know about the party.

Therefore, the correct choice is option (J).

$\"\"$

The correct choice is option (J).