From the table, we can get the following information
number of minutes 0 10 20 30 40 50 60 70
number of people 3 6 3 0 2 0 1 2
The formula for determining average is expressed as
Average = sum of items/number of items
In this case, we have the number of minutes and the frequency of people that made them. Then
Average = (frequency x number of minutes)/total number of people
Thus,
Total number of people = 3 + 6 + 3 + 0 + 2 + 0 + 1 + 2 = 17
Total number of minutes = 3 * 0 + 10 * 6 + 20 * 3 + 30 * 0 + 40 * 2 + 50 * 0 + 60 * 1 + 70 * 2 = 400
Average = 400/17 = 23.5
The number of people that made more than 50 minutes per day is the sum of those that made 60 minutes and those that made 70 minutes. Thus, we have 1 + 2 = 3
3 people made more than 50 minutes per day