Which of the following have the same standard deviation as r, s and t?
I. r-2, s-2, t-2
II.0, s-t, s-r
III. |r|, |s|, |t|
(A) I only
(B) II only
(C) III only
(D) I and II
(E) I and III
SD problem
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I would say I only
In I u r subtracting a constant from each element which has no effect on SD
In III u r taking the absolute value but we dont know how many elements are negative or positive and this may affect SD. It may stay the same or change.
In II SD could change.
I am taking it that this i a must be true question -> A choice that will be true no matter what the individual elements are
OA?
In I u r subtracting a constant from each element which has no effect on SD
In III u r taking the absolute value but we dont know how many elements are negative or positive and this may affect SD. It may stay the same or change.
In II SD could change.
I am taking it that this i a must be true question -> A choice that will be true no matter what the individual elements are
OA?
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I think the answer is D.
since:
-s, -t, -r (if +s) => 0, s-t, s-r
isn't the same as I?
and III is completely different.
so answer is D.
since:
-s, -t, -r (if +s) => 0, s-t, s-r
isn't the same as I?
and III is completely different.
so answer is D.
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Yep and u deserve a +20 or +30 unlike me.I think the answer is D.
U multiply by -1 SD remains same as the original
Add a constant(s) to the -1 multiplied set and the sd remains the same
So 0, s-t, s-r has the same SD as r,s,t
This was a real good one...... Recognizing the sequence of operations was the key and I missed it...
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- logitech
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I was going to try 1,2,3 but since I saw the third option, I tried
r = -1
s = 0
t = 1
1) -3,-2,-1 SD =1
2) 0 , -1, 1 SD =1
3) 1, 0, 1 SD is not 1
So, 1 & 2
r = -1
s = 0
t = 1
1) -3,-2,-1 SD =1
2) 0 , -1, 1 SD =1
3) 1, 0, 1 SD is not 1
So, 1 & 2
LGTCH
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crmaya,
i couldnt get the ques .pls explain...this is gng above my head. wht stem wants to say here.
i couldnt get the ques .pls explain...this is gng above my head. wht stem wants to say here.
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Vivek,
Option 1 -> Add a constant SD does not change
Option II->
When u mutiply the set by -1 the SD does not change
Take s,r,t multiply by -1 you get -s,-r,-t (same SD as s,r,t)
Now add +s (constant) to each of the three elements to get 0,s-r,s-t . This set also has the same SD as s,r,t.
Option III
SD could change since we dont know how many of the elements are negative versus posititve in the list.
Try with 2 numbers negative versus one number negative etc...
Regards,
CR
Option 1 -> Add a constant SD does not change
Option II->
When u mutiply the set by -1 the SD does not change
Take s,r,t multiply by -1 you get -s,-r,-t (same SD as s,r,t)
Now add +s (constant) to each of the three elements to get 0,s-r,s-t . This set also has the same SD as s,r,t.
Option III
SD could change since we dont know how many of the elements are negative versus posititve in the list.
Try with 2 numbers negative versus one number negative etc...
Regards,
CR