Schweser Exam Quant Question annual, correct, standard, security, variation

Benjiko

A security has annual return of 5%, 10%, 15%. The coefficient of variation for the security (using the population standard deviation) is closest to:
A. 0.3
B. 0.4
C. 0.5
D 0.6
My questions is: If it specifies to use the population standard deviation, why do we still have to divide by 3 when calculating the variance and not by 2?
The correct answer was B by the way, and it requires dividing the sum of squared deviations by 3, not by 2.
Thanks in advance

king_kong

if you’re finding the pop s dev, you divide by n and not n1.
it has something to do with allowing less error in the sample s dev if you use n1.
So, you get standard dev. of 4.0825, divide by the mean (10) and get .4

skycfa

Lol, oops, I read pop Stdev and my mind interpreted it as Sample Stdev…
Maybe I should take a study break