Use the insurance dataset to finish the following questions: Show the number of documents in the collection using Aggregation. Only select fields bmi, smoker, from the collection and only display 5 documents in the output. Show the number of documents who is a smoker with age larger than 30. Show the average charges for each region. Show the average charges for records with different number of children excluding those without children (children = 0). Show the average (charges+100) for records with different number of children excluding those without children (children = 0).