need help with giving simple examples to illustrate how mean median and mode are computed, also how to explain the purpose of variance. what does variance measure exactly? how does one compute the variance for sample data versus population data? what is the relation of variance to standard deviation? how can I construct 2 imaginary sample data sets with 5 data values which have the same mean but very different variances? how can I compute the variance and standard deviation for the data sets and explain the meaning of the results to Joan?