Based on prior knowledge and analysis of the relationship between the feature BMXBMI and the task of predicting the age group, we can determine the appropriate ranges of values for each age group.

Considering that BMI is a measure of body fat based on height and weight, the following ranges can be used to classify age groups:

- Adult: 18.5 to 24.9 BMI
- Senior: 25.0 and above BMI

Based on this information, here is the dictionary containing typical BMXBMI values for each age group:

```json
{
	"Adult": [20.5, 21.8, 22.3, 23.7, 24.2],
	"Senior": [25.5, 26.8, 27.3, 28.9, 30.1]
}
```

Please note that these values are just examples and more specific ranges can be determined based on the dataset and domain expertise.