Numerical Measures

I am having major Statistics burnout. I hope someone can please help me with this. I know the range is the largest value minus the smallest value, but that is as far as I got. :(

The annual incomes of the five vice presidents of TMV Industries are: $125,000; $128,000; $122,000; $133,000; and $140,000. Consider this a population. What is the range?

a)What is the range?
b) What is the arithmetic mean income?
c)What is the population variance? The standard deviation?
d) The annual incomes of officers of another firm similar to TMV Industries were also studied. The mean was $129,000 and the standard deviation $8,612. Compare the means and dispersions in the two firms.


TS Contributor
b) the arithmetic mean is just the average --> sum/sample size

c) the population variance is the summation of (x-mu)^2 / n
the standard deviation is the square root of the variance

d) compare the computations in b) and c) to the ones given here