#### Answer

Variance:11.675.
Standard deviation:3.417
Range:11.

#### Work Step by Step

By using the results from before: $\mu=6.5.$
Variance=$\frac{\sum (x-\mu)^2}{n}=\frac{(4-6.5)^2+(4-6.5)^2+...+(15-6.5)^2}{20}=11.675.$
Standard deviation=$\sqrt{variance}=\sqrt{11.675}=3.417$
Range=maximum value-minimum value=$15-4=11$.