Four students from each of the grade levels 4 through 8 at Wilson School were selected at random and surveyed about the number of books they read. The scatterplot above shows the number of complete
independent-reading books, y, that each of the 20 students read during the last school year. A line of best fit
for the data is also shown and has the equation of y = 2x + 4, where x is the grade level of the student.
The mean number of independent-reading books read by the 4 eighth-grade students shown in the
scatterplot is the same as the mean number of independent-reading books read by all 62 eighth-grade
students in the school last year. In total, how many independent-reading books were read by all eighth-
grade students at Wilson School during the last school year?