Question: Suppose that the following table gives the number of thousands of students in grades 9 through 12 for public schools in the u.s. Let X represent the grade level.

Grade (X). 9. 10. 11. 12
Frequency. 3872. 3229. 3119. 2929

A) construct the probability distribution of X
B) calculate the mean of X, and interpret the result
C) calculate the variance of X
D) calculate the standard deviation of X, and interpret the result