9. Solution. To get a complete collection, it is necessary that among Vanya's 10 stickers, there are 6 that Varya is missing. The probability of this is

$$
\frac{C_{6}^{6} \cdot C_{12}^{4}}{C_{18}^{10}}=\frac{5}{442} \approx 0.011
$$
Answer: approximately $0.011$.

## Grading Criteria

| Complete Solution | 3 points |
| :--- | :--- |
| Reasoning is correct, the necessary ratio or product of fractions is set up, but there is a computational error | 2 points |
| No solution or incorrect. | 0 points |

Variant 2