Based on prior knowledge, the feature NGP (Number of legumes per plant) can be used as an indicator of the grain yield of a soybean cultivar. Higher values of NGP are generally associated with a higher yield, while lower values are associated with a lower yield.

To create the dictionary with typical NGP values for each target class, we will assume the following ranges:

- Low NGP values: 0 to 10
- High NGP values: 15 to 25

Here is the dictionary with typical NGP values:

```json
{
	"low": [2.5, 3.2, 4.1, 6.7, 8.9],
	"high": [16.3, 18.5, 20.2, 22.1, 24.8]
}
```

These values represent specific examples within the assumed ranges and can be used to understand the relationship between the NGP feature and the target class (grain yield).