To analyze the relationship between the feature "duration" and the task of whether a client subscribes to a term deposit or not, we can start by looking at the distribution of duration for each target class. Based on prior knowledge, we can determine ranges of values that are relevant for this analysis.

Here's an analysis of the relationship between the feature "duration" and the target class:

- For the "no" target class (clients who do not subscribe to a term deposit), typical duration values might range from very short durations to moderate durations. For example, the durations could be in the range of 0-300 seconds, with typical values like 30, 60, 120, 180, and 240 seconds.

- For the "yes" target class (clients who do subscribe to a term deposit), typical duration values might range from moderate durations to longer durations. For example, the durations could be in the range of 200-2000 seconds, with typical values like 300, 600, 900, 1200, and 1500 seconds.

Based on this analysis, we can create the following dictionary:

```json
{
    "no": [30.0, 60.0, 120.0, 180.0, 240.0],
    "yes": [300.0, 600.0, 900.0, 1200.0, 1500.0]
}
```

Please note that the actual ranges and values may vary depending on the dataset and the specific characteristics of the target class. The ranges provided here are just for illustration purposes.