Based on the given feature, PAQ605, which represents whether the respondent engages in moderate or vigorous-intensity sports, fitness, or recreational activities in a typical week, we can analyze its relationship with the target variable, age group, to determine if it is useful for predicting if a person is a senior or non-senior.

Please note that without access to an actual dataset, it is not possible to determine the exact ranges of values for PAQ605 that would correspond to different age groups. However, based on prior knowledge, we can make some assumptions and provide a general analysis.

Assuming that a higher PAQ605 value represents a person who engages in more physical activities, it is likely that seniors would have lower PAQ605 values compared to non-seniors. This is because as people age, they tend to become less physically active. Therefore, we can expect a negative relationship between PAQ605 and the target age group.

Based on this analysis, I will create a dictionary with example values for PAQ605 for each target class:

```json
{
	"Adult": [1.2, 1.5, 1.8, 2.1, 1.9],
	"Senior": [0.7, 0.9, 0.5, 0.3, 0.8]
}
```

Please note that these values are just examples and may not accurately represent the actual relationship between PAQ605 and the age group target variable.