s = √(Σ(X- x̅ )²/(n-1) ) =0.3775
n=Â Â 9
Confidence level=Â Â 0.80
Degrees of Freedom,  DF=n-1 =   8
alpha,  α=1-CL=  0.2
alpha/2 ,  α/2=  0.1
Lower Chi-Square Value=  χ²1-α/2
=Â Â 3.4895
Upper Chi-Square Value=  χ²α/2 = Â
13.3616
confidence interval for variance is Â
  Â
lower bound=  (n-1)s²/χ²α/2 = Â
0.09
    Â
    Â
upper bound=  (n-1)s²/χ²1-α/2 = Â
0.33
    Â
confidence interval for std dev is  Â
  Â
lower bound=  √(lower bound variance)= Â
0.29
    Â
    Â
upper bound=  √(upper bound of variance= Â
0.57
    Â
