Answer
Variance is $\frac{33}{2}$
Standard Deviation is 4.06
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.
2+6+6+7+-1=20
20/5=4
Mean equals 4
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
$\frac{((2)-6)^{2}+(6-6)^{2}+(6-6)^2+(7-6)^2+((-1)-6)^2}{5-1}$
Which equals 33/2
33/2 is the variance
Step 3 to find the Standard deviation or Sd
you take the square root of the variance
$\sqrt 33/2$
Which approximately equals 4.06
The Sd is 4.06