Answer:
13.33
Step-by-step explanation:
As in the attached diagram, we can see that the points belong to [tex]\mu\pm \sigma[/tex] interval
Data provided in the question as per the details below:
[tex]\mu_{\bar x}[/tex] = 440
[tex]\mu_{\bar x} + \sigma_{\bar x}[/tex] = 480
So,
[tex]\sigma_{\bar x}[/tex] = 480 - 440
= 40
Now the standard deviation of the population is
[tex]V(\bar{x}) = \frac{\sigma}{\sqrt n} \\\\ = \frac{40}{\sqrt 9}[/tex]
= 13.33
Hence, the standard deviation of the population for which the sample is drawn is 13.33
