I have the following problem I'm working on and although I understand the formula's for mean, variance, and standard deviation I don't know which numbers need to be plugged into the formulas.

Here's the Probability Model

# of transactions 0 1 2 3 4 5

Number of Clients56 122 180 140 132 90

I came up with the following porportions

.08 .17 .25 .19 .18 .13

Now for the mean, variance, and standard deviation...The questions states "calculate the mean, variance, and standard deviation for the number of transaction per client for this firm"

-Does this mean I should use # of transactions and porportions for my formula or should I use number of clients and proportions? I also need to know the units of measure for the variance and standard deviation.