Question

−13,9,9,−13,5,−13,9

Calculate the value of the sample standard deviation. Round your answer to one decimal place.

Answer 1

Explanation:

first we need the mean value. this is the sum of all data points divided by the number of data points :

(3×9 + 5 - 3×13)/7 = -7/7 = -1

next, for the standard deviation, we need to sum the squares of the differences of the data points to the mean value, divide that by the number of data points again, and then pull the square root :

(3(-13 - -1)² + 3(9 - -1)² + (5 - -1)²)/7 =

= (3×196 + 3×100 + 36)/7 = (588 + 300 + 36)/7 =

= 924/7 = 132

the standard deviation is now the square root of 132 :

sqrt(132) = 11.48912529... ≈ 11.5

so, yes, as we can see, the numbers vary/deviate rather strongly from the mean value.