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Basic Question 3 of 12

If a teacher computes the mean for a set of test scores and then subtracts this mean from each score, the sum of the resulting set of different scores will equal ______.

A. zero
B. the mean
C. n times the mean

User Contributed Comments 5

User Comment
udhay Can some one explain this please.
VikramJ Not sure why this is the case either. But I just made up an example. Let's say your set is [1,2] with mean 1.5. Subtract 1.5 from each value and you have -0.5 and 0.5 which equal 0..
2014 Sum of deviations from mean is zero.

(4,5,6) 15/3 = 5

4-5= -1
5-5=0
6-6=1

+1-1= 0
msk500 Good explanation, 2014
cosmos1994 1,2,3 mean is 2
new set
-1,0,1 >> -1+0+1=0
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I used your notes and passed ... highly recommended!
Lauren

Lauren

Learning Outcome Statements

calculate and interpret different approaches to return measurement over time and describe their appropriate uses;

CFA® 2025 Level I Curriculum, Volume 1, Module 1.