16, 21, 21, 22, 22, 23, 24, 24, 25, 25, 25, 25, 26, 26, 26, 26, 27, 27, 28, 20, 29, 29, 31, 32, 33, 33, 35, 35, 36, 37
<-- variance
where
and
<-- standard deviation
Depending on the kind of statistic you are trying to work with the might be a . You'll have to check your text or your notes to make sure.
So the first thing to is to calculate the average, , then use that to find the variance.
-Dan