The standard deviation of a data set is 4. What is the variance ?

a. 2

b. 4

c. 8

d. 16

D. 16

Step-by-step explanation:

We know that the standard deviation is the square-root of variance. (+ve sqrt)

Therefore, the variance = (S. D) ^2 = 16

And now ... we go for the second question ...

The z score for a person with marks x is given by (x-mean) / (SD)

Putting in the known values,

Required z-score = (7-13) / 4 = - 6/4 = - 1.5