Question: what is the average time in days between moon phases
[{'answer': '7.4 days', 'provenance': [{'wikipedia_id': '20424', 'title': 'Lunar phase', 'start_paragraph_id': 3, 'start_character': 67, 'end_paragraph_id': 3, 'end_character': 75, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20424', 'title': 'Lunar phase', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 429, 'bleu_score': 0.97451705556073, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8495581725306751912}, 'section': 'Section::::Abstract.'}]}]