Answer
a. Mean 6.4
b. Modal class 6–8
c. Variance 11.6
d. Standard deviation 3.4
Work Step by Step
a. Mean 6.4 (find midpoints of each class, use frequency and group data formula)
b. Modal class 6–8 (class with highest frequency)
c. Variance 11.6 (calculate with a formula)
d. Standard deviation 3.4 (square root of variance)