1) Mean
The mean is given by the sum of the data divided by the number of data (4, in this case):

2) Standard deviation
The standard deviation is given by:

where

is the mean, that we already found at point 1), and N=4. Substituting data, we have:

Answer:
0
Step-by-step explanation:
+25 for the first attempt but -25 for the second
9514 1404 393
Answer:
y was not substituted for every x
Step-by-step explanation:
To find the inverse of ...
y = f(x)
you need to solve ...
x = f(y)
Here, f(x) = x^2 +12x, so f(y) = y^2 +12y
This is not the expression we see on the right of ...
x = y^2 +12x
Apparently y was not properly substituted into f(x).