```json
{
	"low": [1.0, 1.5, 2.0, 2.5, 3.0],
	"high": [3.5, 4.0, 4.5, 5.0, 5.5]
}
```

Based on prior knowledge, the feature NGP (Number of legumes per plant) is likely to have a positive relationship with the task of predicting high grain yield in soybean cultivars. Higher values of NGP usually indicate a healthier and more productive plant, which is likely to result in a higher grain yield.

Therefore, for the target class 'high' (high grain yield), typical NGP values could range from 3.5 to 5.5. The provided values of [3.5, 4.0, 4.5, 5.0, 5.5] can be considered as typical NGP values for soybean cultivars with a high grain yield.

On the other hand, for the target class 'low' (low grain yield), typical NGP values are expected to be lower. In this case, NGP values of [1.0, 1.5, 2.0, 2.5, 3.0] are provided as examples of possible NGP values for soybean cultivars with a low grain yield.