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

828. all there is to it!

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choice b is correct

step-by-step explanation:

we have been given the following system of linear inequalities;

we are required to graphically determine the solution to these system of inequalities. using a graphing tool, the solution is as shown in the attachment below;