Answer:
s = 19.7
Step-by-step explanation:
First we need to calculate the mean x' of the sample as:
[tex]x'=\frac{55+18+39+20+20+44+69}{7}=37.9[/tex]
We sum all the scores and divide them by the number of scores.
Then, the standard deviation s is calculated as:
[tex]s=\sqrt{\frac{(55-37.9)^2+(18-37.9)^2+(39-37.9)^2+(20-37.9)^2+(20-37.9)^2+(44-37.9)^2+(69-37.9)^2}{7-1} }\\ s=19.7[/tex]
We square every score less the mean, sum every value, then divide that by the number of scores less 1 and finally, we calculate the square root.
So, the standard deviation of the sample is 19.7
