Based on the given feature description and task, let's analyze the relationship between feature PAQ605 and the target variable (age group). 

PAQ605 represents the respondent's engagement in moderate or vigorous-intensity sports, fitness, or recreational activities in a typical week. A value of 1 indicates that the respondent takes part in weekly moderate or vigorous-intensity physical activities, while a value of 2 indicates that they do not.

Based on prior knowledge and assumptions, we can make the following analysis:

- For the 'Adult' age group, there is likely to be a mix of individuals who engage in moderate or vigorous-intensity activities and those who do not. Therefore, we expect to see both 1's and 2's in the values of PAQ605 for this age group.

- For the 'Senior' age group, we can assume that there will be fewer individuals engaging in vigorous-intensity activities due to age-related factors. Therefore, we might see more 2's (indicating no engagement in such activities) for this age group compared to the 'Adult' age group.

Based on this analysis, the dictionary with the requested format can be generated as follows:

```json
{
	"Adult": [1.0, 1.0, 2.0, 2.0, 1.0], 
	"Senior": [1.0, 2.0, 2.0, 2.0, 2.0]
}
```

Please note that the values in the lists are just examples and represent the possible values of feature PAQ605 for each target class. The actual values may vary based on the specific dataset or context.