i can help with (a) and (b), i should be able to help with (e), but i forgot the formula for the standard deviation. does anyone know an easy way to remember it? and the other formulas as well? i'm looking for any mnemonic that anyone might know.

(a) the mean is the average of all the numbers found in the following way:

(b) The median is the middle number when the list of numbers is arranged from lowest to highest. Note that if there is an odd number of numbers, the median is, in fact, the middle number. If there is an even number of numbers, the median is the mean of the two middle numbers