If d is the mean of x, y, and z, what is the mean x - 5, y - 5, z - 5 ?
Choose one:
A) d
B) 3d
C) 15d
D) d - 5
E) d + 15
If we add or subtract a constant to each term in a set:   Mean will increase or decrease by the same constant.   SD will not change.   If we increase or decrease each term in a set by the same percent (multiply by a constant):   Mean will increase or decrease by the same percent.   SD will increase or decrease by the same percent.   So in our case mean will decrease by 5, as we are subtracting 5 from each term in a set --&gt; Mean =d - 5.   Answer: d - 5.
<result>D</result>
If d is the mean of x, y, and z, what is the mean x - 5, y - 5, z - 5 ?