
The mean shift upwards by $1000 and we add this to the salary, so we put a $1000 over here

and 1 over here because it's the old mean plus $1000.

For the standard deviation, that's interesting. Let's look at the variance, which is defined as follows.

And now let's add for the new variance, a $1000 to each individual salary and a $1000 to the mean.

As you can see, these $1000 cancels them out and you have the formula for the old variance.

Hence, the old standard deviation, which means you put 1 over here and 0 over here.