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Re: New DS set!!!
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11 Apr 2013, 09:23
QUESTION 5
A={3 -2x, 3-x , 3, 3+x, 3+2x} -> mean = 3, deviations from the mean: 2x, x, 0, x, 2x
B={3- 2x, 3-x , 3, 3+x, 3+2x, y} -> mean = (15/6 +y/6),
(1) SD of A is positive, then x>0. (no other restrictions on x, so let's take for example x = 1). The deviations
of set A are 2, 1,1,2. If y is a gigantic number, and x = 1, it is obvious that the deviations from the mean in set B
will be much higher than 2, 1,0,1,2. However, if y = 3, the deviations will also be 2,1,1,2.
INSUFFICIENT
(2) y = 3, means that the mean for set B = 3, and deviations are: 2x, x,0,0,x,2x. Therefore SD for B and A are the same.
SUFFICIENT
ANS: B