To compute the mean, you simply have to sum all the elments in the data set and the divide the sum by the number of elements:

To compute the variance, we first need to compute the distance of each element from the mean. To do so, we build a "parallel" dataset, given by the difference of every value and the mean:


Now we need those difference squared:

The variance is the mean of this new vector, so

Finally, the standard deviation is simply the square root of the variance, so you have

If you mean 720/10^3, you do 10*10*10. This equals 1000. Now, do 720/1000. This is 0.72, or 72/100, which is your answer.
This depends on how many friends she has. Like if she has 72 friends each will get one of each, but if she has 3 friends than each will get 24 on each. Do you know how many friends she has?
Divide 30 by 10. 30mph/10seconds = 3mph/seconds
Answer:
$337.5
Step-by-step explanation:
He would get $337.5 because if he gets $11.25 every hour you just multiply $11.25 by 30 hours.