Based on prior knowledge, we can determine the following general ranges for Body Mass Index (BMXBMI) to classify individuals as either adults or seniors:

- Adult: BMXBMI values between 18.5 and 24.9.
- Senior: BMXBMI values greater than or equal to 24.9.

Here is the generated dictionary:

```json
{
	"Adult": [21.3, 22.7, 19.9, 24.0, 20.5],
	"Senior": [26.5, 28.9, 25.3, 27.8, 30.1]
}
```

Please note that the values provided in the dictionary are just examples and represent typical BMXBMI values for each target class.