Consider the following partially completed grouped frequency distribution of test scores for 60 students.
Class Interval | Frequency
50–59 | 8
60–69 | m
70–79 | m+4
80–89 | 2m−6
90–99 | 10
Given that the total number of students is 60, determine the value of m.
a) 10
b) 11
c) 9
d) 12