Analysis:
In order to determine the appropriate ranges of values for the feature LBXIN that would correspond to 'Adult' and 'Senior' age groups, we need to consider the typical insulin levels in these groups. 

Based on prior knowledge, blood insulin levels tend to increase with age. However, there is no specific threshold that defines seniority in relation to blood insulin levels. 

To determine the appropriate ranges, we can assume that 'Adult' age group corresponds to individuals below a certain insulin level, and 'Senior' age group corresponds to those above that level. 

Let's assume an arbitrary threshold of 10 for the blood insulin level to distinguish 'Adult' and 'Senior' age groups.

Dictionary:
```json
{
    "Adult": [4.2, 5.6, 6.8, 8.3, 9.4],
    "Senior": [11.1, 12.5, 13.2, 14.8, 16.3]
}
```
Note that these values are just examples and may not represent the true distribution of blood insulin levels for the respective age groups.