I'll be honest: I missed the day this was gone over in class and I can't find it in my book. I understand the policy on homework questions so I will post the question and what I've done and hopefully someone can just help me understand it. I'm not asking for answers, just help.

"In each of the following, describe how the mean and the standard deviation of a data set are affected."

a) The number 10 is added to each value of the data set.

b) Each value of the data set is multiplied by 2.

c) each value of the data set is multiplied by -2.

I made a data set and calculated it's mean and standard deviation and then added 10 to each number in the data set and the mean increased by 10 while the standard deviation stayed the same. When I multiplied each number by 2 both the mean and the standard deviation changed. I'm not sure if the numbers are supposed to behave this way or if I'm doing something wrong. (I am NEVER missing a class again come hell or high water!!!)

Any help is greatly appreciated.