Calculating Standard Deviation (GRE Way)

Question 1

1) Find the Average of the Data Set

2) Find the Distance of Each Value from the Mean

3) To Find the Standard Deviation, Take the Average of the Distances

Answer 1

Example:

Find the standard deviation of this data set: 1, 6, 8, 10, 12, and 17

1) Find the Average of the Data Set
1 + 6 + 8 + 10 + 12 + 17

6

= 54/6 = 9

2) Find the Distance of Each Value from the Mean

9 - 1 = 8

9 - 6 = 3

9 - 8 = 1

10 - 9 = 1

12 - 9 = 3

17 - 9 = 8

3) To Find the Standard Deviation, Take the Average of the Distances

8 + 3 + 1 + 1 + 3 + 8

6

= 24/6 = 4

The standard deviation for this set of data is 4.