1.9, 1.9, 2.8, 3.9, 4.2, 5.7, 7.2, 8.6
lets start with range. take the lowest and the highest and that is the range
Range = [1.9, 8.6]
to get the mean add them together and divide by the number of occurences.
M = 1.9 + 1.9 + 2.8 + 3.9 + 4.2 + 5.7 + 7.2 + 8.6 / 8
Mean = 36.2 / 8 = 4.525
Mode = 1.9
take the number and subtract the mean then square it and total them all.
stddev = [(1.9 - 4.525)^2 + (1.9 - 4.525)^2 + (2.8 - 4.525)^2 + (3.9 - 4.525)^2 + (4.2 - 4.525)^2 + (5.7 - 4.525)^2 + (7.2 - 4.525)^2 + (8.6 - 4.525)^2]/8
I am going to round to tenths place.
stddev = [6.9 + 6.9 + 3.0 + .4 + .1 + 1.4 + 7.2 + 16.6 ]/ 8
stddev = 42.5 / 8 = 5.3