#### Answer

Range:2.95 Richter scale, variance:0.34 Richter scale, standard 0.583 Richter scale.

#### Work Step by Step

Range is the difference of the maximum and minimum of the set: range=2.95-0=2.95 Richter scale. Calculated by calculator, the mean is: 1.184 Richter scale. The variance is the sum of the differences of each value and the mean on the power of two, divided by the number of values minus 1: variance=$\frac{(0.7-1.184)^2+(2.2-1.184)^2+...+(1.39-1.184)^2}{50-1}=0.34 Richter scale.$ The standard deviation is the square root of the variance: standard deviation=$\sqrt{0.34}=0.583 Richter scale$