If d is the standard deviation x, y, and z, what is the standard deviation of x + 10, y + 10, z + 10 ? Answers:  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 SD won't change as we are adding 10 to each term in a set --&gt; SD=d.   dnswer: d.
<result>A</result>
If d is the standard deviation x, y, and z, what is the standard deviation of x + 10, y + 10, z + 10 ?