Answer
a. Range = 42, variance = 154.3447, standard deviation = 12.4326
b. Coefficient of variation = 22.32%
c. Sample statistics
Work Step by Step
a. Range = Highest Value - Lowest Value = 77-35 = 42
$Variance = σ^2=(∑〖(x-μ)〗^2 )/n-1 $
$=[∑(x^2) -∑(x)^2]/N/n-1$
$=[64871-(1113^{2}/20)/19]$
$=(64871-61938.45)/19$
$=154.3447$
Standard Deviation = $\sqrt 154.3447 = 12.4326$
b. Coefficient of Variation=$12.4326\div55.65\times100% =22.32%$
c. The values are sample statistics, because the data collected are 20 randomly selected workers among all the workers.
