Answer:
C. The mean of the data set is 8.
Step-by-step explanation:
From the dot plot we can make a frequency table as follows:
Number of books read            Frequency
    6                            2 Â
    7                            2
    8                            2
    9                            2
    10                            2
Since, the number of dots are  10 or then sum of the frequencies is 10.
      Hence, the number of observations are 10.
Also, the median of the set is: 8
Now, the mean is calculated as:
         Hence, Mean of the data set is: 8
Now, the range of the data set is the difference between the minimum and the maximum value.
         Hence, range=10-6=4
      The range of the data set is 4.
