A data set of 20 integers is summarized in the histogram shown. The first interval represents the frequency of integers greater than or equal to 0 but less than 10, the second interval represents the frequency of integers greater than or equal to 10 but less than 20, and so on.
Interval [0,10): Frequency 5
Interval [10,20): Frequency 8
Interval [20,30): Frequency 7
What is the greatest possible value of the mean of this data set?
