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by nitya34 » Mon Jul 13, 2009 6:18 am
Which data set has the greater standard deviation, data set K or data set L ?

(1) Every element in data set K is a multiple of 3.

(2) Every element in data set L is a multiple of 9.


OA is............ E...............Thanks
Last edited by nitya34 on Mon Jul 13, 2009 11:19 pm, edited 1 time in total.
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by niraj_a » Mon Jul 13, 2009 6:39 am
not sure between C and E. i guess E.

since both sets contain numbers that are evenly spaced, the mean = median for both sets. but, if one set has more / less numbers than the other set, then the actual value of the mean, and by extension, the actual value of the SD could be different.

i sure hope i'm right.
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by tohellandback » Mon Jul 13, 2009 7:11 am
IMO E
consider sets {3,6,9} and {9}
now consider sets {3} and {9,18,27}
The powers of two are bloody impolite!!
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by david2008 » Mon Jul 13, 2009 2:04 pm
Yup should be E

SD depends on number of items in the set as well as the mean and distribution of the numbers. Any 1 element set would have a 0 SD so by not knowing the number of numbers in each set, we can't conclude what the relative SD is,
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by shibal » Mon Jul 13, 2009 4:59 pm
E

K could be 3,3,3 or 3,6,9,12
L could be 9,9,9 or 9,18,27
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by mehravikas » Mon Jul 13, 2009 7:39 pm
Standard deviation changes when the numbers in the set are multiplied / divided by the same constant. However we dont know here how many elements are there in both the sets and the range of the set.

Therefore answer should be E.
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by aj5105 » Mon Jul 13, 2009 9:03 pm
right said. (E). we need to know the number of elements in the set.
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