the ages (in years) of a random sample of shoppers at a gaming store are shown. determine the range, mean, variance, and standard deviation of the...

the ages​ (in years) of a random sample of shoppers at a gaming store are shown. determine the ​​range, mean, variance, and standard deviation of the sample data set.12,16​,23​,14​,17​,16​,19​,16​,15​,18.

I don't understand how to get the variance and standard deviation. I got the range and mean. I have been working on this for over an hour. please just show me what I need to do. Thanks in advance.