What is the standard deviations of {1,3,5,5,7,9,10,11,13,15,15,17,17,17}?

1 Answer
Nov 12, 2015

Assuming you mean population standard deviation, then #sigma = 5.3132#

Explanation:

Calculate Mean (Average) denoted as μ

#mu = frac(Sigma_n)(n)#

#mu = frac(1 + 3 + 5 + 5 + 7 + 9 + 10 + 11 + 13 + 15 + 15 + 17 + 17 + 17)(14)#

#mu = frac(145)(14)#

#mu = 10.357142857143#

Let's evaluate the square difference from the mean of each term #(X_i - mu)^2#:

#(X_1 - mu)^2 = (1 - 10.357142857143)^2 = -9.35714285714292 = 87.55612244898#

#(X_2 - μ)^2 = (3 - 10.357142857143)^2 = -7.3571428571429^2 = 54.127551020408#

#(X_3 - μ)^2 = (5 - 10.357142857143)^2 = -5.3571428571429^2 = 28.698979591837#

#(X_4 - μ)^2 = (5 - 10.357142857143)^2 = -5.3571428571429^2 = 28.698979591837#

#(X_5 - μ)^2 = (7 - 10.357142857143)^2 = -3.3571428571429^2 = 11.270408163265#

#(X_6 - μ)^2 = (9 - 10.357142857143)^2 = -1.3571428571429^2 = 1.8418367346939#

#(X_7 - μ)^2 = (10 - 10.357142857143)^2 = -0.35714285714286^2 = 0.12755102040816#

#(X_8 - μ)^2 = (11 - 10.357142857143)^2 = 0.64285714285714^2 = 0.41326530612245#

#(X_9 - μ)^2 = (13 - 10.357142857143)^2 = 2.6428571428571^2 = 6.984693877551#

#(X_10 - μ)^2 = (15 - 10.357142857143)^2 = 4.6428571428571^2 = 21.55612244898#

#(X_11 - μ)^2 = (15 - 10.357142857143)^2 = 4.6428571428571^2 = 21.55612244898#

#(X_12 - μ)^2 = (17 - 10.357142857143)^2 = 6.6428571428571^2 = 44.127551020408#

#(X_13 - μ)^2 = (17 - 10.357142857143)^2 = 6.6428571428571^2 = 44.127551020408#

#(X_14 - μ)^2 = (17 - 10.357142857143)^2 = 6.6428571428571^2 = 44.127551020408#

Add up the terms:

#ΣE(X_i - μ)^2 = 87.55612244898 + 54.127551020408 + 28.698979591837 + 28.698979591837 + 11.270408163265 + 1.8418367346939 + 0.12755102040816 + 0.41326530612245 + 6.984693877551 + 21.55612244898 + 21.55612244898 + 44.127551020408 + 44.127551020408 + 44.127551020408#

#ΣE(X_i - μ)2 = 395.21428571429#

Calculate Variance
#σ^2 = frac(ΣE(X_i - μ)^2)(n)#

#σ^2 = frac(395.21428571429)(14)#

#σ^2 = 28.229591836735#

Calculate Standard Deviation:

#σ = sqrt(σ^2) = sqrt(28.229591836735)#

#sigma = 5.3132#

Statistics Calculator