Can some please help me!

Question

For the following distributions, draw the approximate shape and identify what scores would correspond to ONE standard deviation unit above and below the mean.

A). Distribution #1, mean = 45, Sx = 22.5 B). Distribution #2, mean = 45, Sx = 5.5 C). Distribution #3, mean = 45, Sx = 12.5

Answer 1

Assuming these are Normal distributions they are all symmetric bell curves centered at the mean = 45.  The first one has the largest standard deviation so it is the broadest, or most spread out.  The second one has the smallest standard deviation so it is the narrowest.  The third one lies in between.  A general rule of thumb is that the distributions get pretty close to 0 when you are about 3 standard deviations away from the mean.  

 

To find the score that is one standard deviation above the mean just add Sx to the mean.  For one standard deviation below just subtract Sx from the mean.