Based on my prior knowledge, blood insulin levels can vary depending on a person's age, health condition, and other factors. It is generally accepted that insulin levels tend to increase with age in the general population. However, insulin levels can also vary greatly between individuals.

To analyze the relationship between the feature LBXIN (Respondent's Blood Insulin Levels) and the task of predicting age groups (Senior or non-senior), we can consider the typical ranges of blood insulin levels for each age group.

Based on general information, I will assume that insulin levels above 20 µIU/mL may indicate higher insulin resistance and potentially higher risk for health issues such as diabetes. However, these values can vary depending on the specific context and dataset.

Here is a dictionary with typical LBXIN values for each target class:

```json
{
	"Adult": [10.5, 12.8, 15.3, 18.9, 22.1],
	"Senior": [16.2, 19.7, 23.4, 27.9, 31.2]
}
```

Please note that these values are just examples and should be adjusted based on the specific context and dataset.