Based on prior knowledge, we can analyze the relationship between the feature BMXBMI and the target variable (age group) to determine the appropriate ranges of values.

For this task, we can assume that "Senior" refers to individuals who are older (typically above a certain age threshold) and "Adult" refers to individuals below that age threshold.

A common approach to classify BMI ranges is to use the World Health Organization's (WHO) classification. According to WHO, BMI can be categorized as follows:

- Underweight: BMI < 18.5
- Normal weight: 18.5 <= BMI < 25
- Overweight: 25 <= BMI < 30
- Obesity Class I: 30 <= BMI < 35
- Obesity Class II: 35 <= BMI < 40
- Obesity Class III: BMI >= 40

To determine the appropriate ranges of values for "Adult" and "Senior" age groups, we need more information about the specific age threshold that defines the two groups. Without this information, we can't assign exact ranges for the groups.

However, we can still provide the requested dictionary with 5 typical BMXBMI values for each target class, based on the assumption that "Senior" individuals might generally have higher BMXBMI values compared to "Adult" individuals.

```json
{
	"Adult": [18.5, 21.3, 23.8, 24.9, 26.7],
	"Senior": [25.3, 27.6, 29.4, 30.8, 35.2]
}
```

Please note that without specific age threshold information, these values are just hypothetical examples based on the assumption mentioned above.