How do you calculate the sample standard deviation from a set of scores with a mean of 20 and a variance of 9, if the sample size is 25?

To find the sample standard deviation (SD) from the given data, we can follow a straightforward process:

1. Understand the terms:
   • The mean (m) of your sample is 20.
   • The variance (s²) is 9.
   • The sample size (n) is 25.
2. Find the sample standard deviation:

   The sample standard deviation (SD) is the square root of the variance. It gives you an idea of how spread out the scores are from the mean.

   The formula to compute the sample standard deviation (s) is:

   s = √s²

3. Calculate:

   Substituting the known variance into the formula:

   s = √9

   s = 3

So, the sample standard deviation for your scores is 3.