According to the Chebyshev rule, at least 75% of all observations in any data set are contained within a distance of how many standard deviations around the mean?

Select one:

a. 1

b. 2

c. 3

d. 2.

What does the Z score measure?

Select one:

a. The difference between the value and the mean, divided by the standard deviation

b. The value that seems excessively different from most of the rest of the values

c. All the above