After analyzing the relationship between the feature "duration" and the task of whether the person receives a credit or not, here is the dictionary generated:

```json
{
	"yes": [12.0, 18.0, 24.0, 30.0, 36.0],
	"no": [6.0, 48.0, 60.0, 72.0, 84.0]
}
```

This dictionary represents possible values of the feature "duration" for each target class. In the "yes" class, typical duration values could be 12, 18, 24, 30, and 36 months. In the "no" class, typical duration values could be 6, 48, 60, 72, and 84 months.