SD with values

Which set has the greatest standard deviation?

I. 1, 3, 5, 7, 9
II. 2, 4, 6, 8, 10
III. 1, -1, -3, -5, -7

(A) I
(B) II
(C) III
(D) I and II
(E) none

i AM CONFUSED WITH THE THIRD SET .... ARE WE ADDING IT .THEN TOTAL = 15,MEAN = 15/3 =5
IS IT CORRECT?

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killer1387: Legendary Member; Posts: 581; Joined: Sun Apr 03, 2011 7:53 am; Thanked: 52 times; Followed by:5 members

by killer1387 » Thu Mar 08, 2012 8:37 pm

ruplun wrote:Which set has the greatest standard deviation?

I. 1, 3, 5, 7, 9
II. 2, 4, 6, 8, 10
III. 1, -1, -3, -5, -7

(A) I
(B) II
(C) III
(D) I and II
(E) none

i AM CONFUSED WITH THE THIRD SET .... ARE WE ADDING IT .THEN TOTAL = 15,MEAN = 15/3 =5
IS IT CORRECT?

IMO E,
THE BOLD PART IS INCORRECT
IT SHOULD BE

(1-1-3-5-7)/5= -3. Also the series is evenly spaced you dont need to perform this calculation for mean its just the middle term i.e. -3.

HTH

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