Interpreting Normal Distributions

I’m stuck on a Statistics question and need an explanation.

Collapse SubdiscussionCurtis Brown

Good overall work, Titty, except you should have THREE z-scores, one for each of three different months you select.

So, can you check your z-scores again?

Remember, take the BILL and “subtract” the MEAN. Then, “divide” that value by the STANDARD DEVIATION. This will be the z-score.

(Basically, the z-score tells us how many standard deviations a value is above or below the mean.)

Doctor Ralph, My instructor asked me the above question from the answer I posted. Can you kindly answer this question above? Thanks.