Answer
Variance is 6.64
Standard deviation is 2.58
Work Step by Step
Step 1
First find the mean of the data set which is found by adding up all the numbers and dividing by the number of numbers.
1/2+3/2+-4+5/4=-.75
-.75/4=-.1875
Mean equals -.1875
Step 2
Variance is found by the equation
$\frac{(s1−M)^2+(s2−M)^2}{N−1}$
Where s is the sample
M is the mean and
N is the number of samples
So the final equation should look like
$\frac{(1/2−-.1875)^2+(3/2−-.1875)^2+(-4−-.18752)^2+(5/4−-.1875)^2}{4-1}$
Which equals 6.64
6.64 is the variance
Step 3
to find the Standard deviation or Sd
you take the square root of the variance
$\sqrt (6.64)$
Which approximately equals 2.58
The Sd is 2.58