LBXGLU is the respondent's blood glucose level after fasting, which is a numeric variable. In order to determine appropriate ranges for the feature values, we can refer to medical guidelines.

Based on medical guidelines, a normal blood glucose level after fasting is typically between 70 and 99 mg/dL. However, the definition of a "senior" age group can vary, so we will assume that individuals above the age of 65 are considered seniors.

Considering this information, we can analyze the relationship between the LBXGLU feature and the target class to determine typical LBXGLU values for each age group.

Here is the dictionary containing the typical LBXGLU values for each target class:

```json
{
	"Adult": [90.5, 92.1, 88.3, 94.7, 97.2],
	"Senior": [105.2, 108.6, 102.1, 112.9, 110.3]
}
```

Please note that these LBXGLU values are just examples and should not be considered as precise cut-off points for determining age groups. The actual age group classification should be done using a proper statistical model or domain knowledge in the field of healthcare.